Case No: (1) CO/1521/2016 
& (2) CO/1673/2016
Neutral Citation Number: [2016] EWHC 1772 (Admin)
IN THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION
PLANNING COURT

Royal Courts of Justice
Strand, London, WC2A 2LL

Date: 15 July 2016

Before :

DAVID ELVIN QC
(Sitting as a Deputy High Court Judge)

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Between :

	(1)	STOKE POGES PARISH COUNCIL
(2)	SOUTH BUCKINGHAMSHIRE DISTRICT COUNCIL	Claimants	
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(CO/1521/2016)	(1)	SECRETARY OF STATE FOR COMMUNITIES AND LOCAL GOVERNMENT 
(2)	SECRETARY OF STATE FOR EDUCATION 
(3)	SOUTH BUCKINGHAMSHIRE DISTRICT COUNCIL 
(4)	SLOUGH SIKH EDUCATION TRUST LIMITED	Defendants	

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Guy Williams and Heather Sargent (instructed by Leigh Day) 
for Stoke Poges Parish Council
Juan Lopez (instructed by Sharpe Pritchard) for South Bucks District Council
Stephen Whale (instructed by Government Legal Dept.) for the First Defendant
James Maurici QC (instructed by Government Legal Dept.) for the Second Defendant

Hearing date: 12 July 2016

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Judgment
David Elvin QC : 
Introduction 
1.	Stoke Poges Parish Council (“SPPC”) and South Buckinghamshire District Council (“SBDC”) both apply for permission under s.288(4A) of the Town & Country Planning Act 1990 to bring a challenge to the First Defendant’s decision letter dated 18.2.16 (“DL”) to grant prior approval to the Secretary of State for Education (“SSE”) under Class T, paras. T.2(1)(b) and W of Part 3 of Schedule 2 to the Town & Country Planning (General Permitted Development) (England) Order 2015 (“GPDO”) for a change of use from offices to a state funded school at Pioneer House, Hollybush Hill, Stoke Poges. The school is proposed for occupation by the Khalsa Academy, which is a Sikh faith free school which in September 2013 occupied Pioneer House and began to use it as a school pursuant to temporary use permitted development rights.
2.	The DL was a redetermination of a decision originally made in September 2014 which was quashed by consent by this Court on 9.3.15. It followed the refusal of SSE’s application made in November 2013 for prior approval by SBDC on a number of grounds (restricted to those three issues now set out in Class T.2.(1)(b)) and SSE’s appeal. The original applications were made under the predecessor GPDO (Class K) but the redetermination was made under the current provisions. Nothing turns on this.
3.	Although the s.288 challenges both relate to the issue of noise, and its treatment in the DL, the noise issue was raised relatively late in the day by SBDC (see IR 3.6) but prior to the holding of the hearing into SSE’s appeal, which took place by way of informal hearing before the Inspector, Ava Wood DipArch MRTPI, on 10 and 11.7.14. As is usual, the Inspector carried out a site visit, but it is accepted that her visit did not coincide with a time when the school children were outside in the playground. Since the School at the time had only 90 pupils, it is also accepted that the Inspector was unable to perceive the effect of a school with 840 pupils, which had to be judged based on the noise experts’ evidence and their assessments of likely impact.
4.	The Inspector’s report (“IR”) dealt with a number of other grounds in addition to noise, namely highways/transportation and contamination, but it was the issue of noise which led to her recommendation to refuse approval. It is not necessary to consider the aspects of her report other than those relating to noise.
5.	The applications were made separately by SPPC and SBDC but by consent were listed to be heard together and on 9.5.16 Gilbart J. ordered that there should be a rolled-up hearing of permission and the substantive challenge in both cases.
6.	In dealing with the rolled up issues, it is simpler if I deal with the substance of the grounds then at the end address the question of permission and substantive relief.
7.	I am grateful to all counsel for their helpful and succinct submissions.
The context of the noise issue
8.	The issue was whether the noise impact of the proposed school, which might eventually accommodate 840 pupils, would have such an adverse impact on the amenity of local residents that prior approval should be refused i.e. whether there was a “significant adverse impact on health and quality of life”. 
9.	The planning policy context is set by para. 123 of the National Planning Policy Framework (“NPPF”):
“123. Planning policies and decisions should aim to: 
● avoid noise from giving rise to significant adverse impacts27 on health and quality of life as a result of new development; 
● mitigate and reduce to a minimum other adverse impacts27 on health and quality of life arising from noise from new development, including through the use of conditions; 
● recognise that development will often create some noise and existing businesses wanting to develop in continuance of their business should not have unreasonable restrictions put on them because of changes in nearby land uses since they were established; and 
● identify and protect areas of tranquillity which have remained relatively undisturbed by noise and are prized for their recreational and amenity value for this reason...”
Footnote 27 refers to “See Explanatory Note to the Noise Policy Statement for England.”
10.	At the hearing each of the SSE, SBDC and SPPC were represented and called acoustic experts. While a short statement of common ground was agreed by the three experts during the hearing (“SOCG”), it did not resolve issues and it is apparent from the IR and SSE’s closing submissions that a number of significant matters remained in issue.
11.	The experts agreed the relevant guidance which they set out in the SOCG. The Inspector and Secretary of State were referred to relevant national noise policy in para. 123 of the NPPF and Section 30 of the national Planning Policy Guidance (“PPG”) “Noise” as well as to the Noise Policy Statement for England (March 2010) (“NPSE”). None of those documents describes noise impacts in anything other than subjective qualitative terms and sets no specific noise thresholds or levels even for guidance purposes. The position is summarised by the NPSE at 2.9:
“2.9 Noise management is a complex issue and at times requires complex solutions. Unlike air quality, there are currently no European or national noise limits which have to be met, although there can be specific local limits for specific developments. Furthermore, sound only becomes noise (often defined as “unwanted sound”) when it exists in the wrong place or at the wrong time such that it causes or contributes to some harmful or otherwise unwanted effect, like annoyance or sleep disturbance. Unlike many other pollutants, noise pollution depends not just on the physical aspects of the sound itself, but also the human reaction to it. Consequently, the NPSE provides a clear description of desired outcome from the noise management of a particular situation.”
12.	Seeking more specific guidance than the NPPF, PPG and NPSE, the experts referred to BS 8233:2014 “Guidance on sound insulation and noise reduction for buildings” which, whilst relied on by all parties’ experts, is specific to the design of new buildings. Indeed, this is made clear at Section 1, “Scope”:
“This British Standard provides guidance for the control of noise in and around buildings. It is applicable to the design of new buildings, or refurbished buildings undergoing a change of use, but does not provide guidance on assessing the effects of changes in the external noise levels to occupants of an existing building.”
13.	The consequence of this, as the Claimants accepted, is that some caution has to be applied to reading BS8233 since it is written from the perspective of advising on the design of new buildings and not applying standards to determine the acceptability of impacts on buildings from development taking place elsewhere.
14.	The parties also agreed that reference should be made to the World Health Organisation “Guidelines for Community Noise” (1999) which are drawn upon in the BS and referenced in the NPSE. 
15.	It is common ground between the parties that the First Defendant was entitled to treat the threshold noise values in the BS and WHO guidance as guidance only, as he did: see below. Indeed, that guidance is not national policy nor has it been produced as such. However, Mr Williams and Mr Lopez both point out that, nonetheless, the guidance has to be properly understood in the first place.
The Inspector’s Report
16.	At Section 2 of the IR the Inspector described the appeal site and its surroundings, which included another school:
“2.1 Pioneer House is a freestanding two/three storey modern building erected in the early 1990s for Class B1 office use. It occupies an irregular piece of land extending to some 4 Ha. The site includes areas of hard surface car parking to the front of the building and further spaces laid out at the north western corner of the site. There is additionally a large hard surfaced area extending in an arc at the rear of the building; it was originally laid out for parking purposes but is regularly used by the school (currently occupying part of the building) as a hard surfaced outdoor play area. An open grassed field, extending across much of the southern extent of the appeal site, is also used by the school for outdoor play. The site lies within the Metropolitan Green Belt.
2.2 The premises are served from two access points on Hollybush Hill to the north. There are residential properties adjoining the north western boundary, and part of the eastern and western boundaries of the site. A school operated by the Plymouth Brethren, occupying what was the original Victorian village primary school, is located at the south western corner of Pioneer House. I was told the Brethren school currently accommodates 98 pupils but the building has capacity for 200.
2.3 Hollybush Hill is primarily a residential street, linking Bells Hill (Gerrards Cross Road) to the west with Framewood Road to the east. The site is bound by School Lane to its west and south and by Hockley Lane and Hockley Lane properties to the east. The Stoke Poges village centre is located on Bells Hill. Industrial areas referred to in evidence are situated on Bells Hill and Framewood Road.”
17.	The Inspector described the proposal in IR Section 4 as follows:
“4.1 The proposal is for a Sikh faith-based secondary school to accommodate 840 pupils and 70 members of staff by 2018. The school will cater for cohorts aged 11-18 years and is to include a sixth form for 240 students. At present the school is occupied by 90 pupils in 4 classes. The intention is to create a multi-cultural school based on Sikh principles. Under the admissions policy, the Academy will admit 50% pupils from Sikh backgrounds and 50% of other or no faiths. In the event that fewer than 50% of other or no faiths apply, the remaining places will be allocated to those of the Sikh faith.
4.2 The school timetable indicates that the school day starts when the pupils begin to arrive at 07:30 hours and extends to 16:45. As there is not provision on site for indoor sporting activities, the school will need to look at local sports provision from Year 3 of operation onwards. It is said that much of the school’s sporting provision will be provided off-site. Currently, there are two options locally being considered but none has been selected and there are no arrangements in place. There is to be no weekend sporting or other activities at the site, save for an open event to be held annually on school premises at a weekend.”
18.	The Inspector dealt with planning policy, planning history (as to which the parties were agreed that previous noise restrictions imposed on the office development were unenforceable), the parties’ cases on the issues arising and set out her conclusions in Section 12. She dealt with noise at IR 12.3.1 to 12.3.19. Having dealt with the unenforceable conditions, the Inspector addressed a key consideration, namely the specific noise impact context:
“12.3.3 The consultants further agreed that the impact of noise on residents arises not from any internal activities but from use of the car park to the south side of the building for external school activities. These range from informal outdoor activities during break and lunch periods as well as organised sports. During the summer months the latter would take place (as it does now) on the field to the south. [6.3.1]
12.3.4 The term time schedule confirms the arrival time between 07:30 and 08:00, though residents claim that that pupils can arrive as early as 07:10. The schedule includes a 20 minute morning break period when 600 pupils can be expected to be in the playground area (sixth formers are expected to use internal common rooms). A staggered lunch period of between 12:50 and 13:30 could see up to 400 pupils outdoors. Up to 100 pupils are expected to take part in outdoor activities during the enrichment period between 15:45 and 16:45. Each class in years 7-11 would also undertake up to one period of PE per week, comprising a combination of internal and external lessons but no more than 30 pupils would be outdoors in any one period. Main sports lessons and sports for sixth formers would take place off site. No weekend activities are expected to take place, save for the single annual event. [4.2, 11.1.5]”
19.	The Inspector turned to the critical issue, namely the impact of noise from the proposed school on local residents in School Lane and Hockley Lane. She began:
“12.3.6 To assess what impact the school and its operations would have on the neighbours at School Lane and Hockley Lane, the starting point must be an objective assessment of the predicted noise levels against the range of guidance referred to by the main parties. [6.3.5]”
20.	Noise impacts arose both with regard to internal noise levels, both with and without open windows, and noise levels affecting the use of gardens and other residential amenity space. There was no issue with the agreed noise levels with the impact on internal spaces in the dwellings if the windows were closed:
“12.3.7 It was agreed that, with windows closed and the school external areas in use, noise levels within adjacent affected dwellings would achieve the recommended internal noise levels described in Table 4 of BS8233:2014. [6.3.1]”
21.	Nonetheless, issues arose with regard to internal noise levels where windows (or patio doors) were open and external noise levels for residential amenity space such as gardens, balconies and outdoor seating areas. 
22.	With regard to internal noise levels with windows etc open, the Inspector considered the impacts would be unacceptable:
“12.3.8 SBDC’s noise consultant could not point to any guidance to support his use of the 5 and 10dBA noise reduction factors for partially open windows nor the 0-5dBA for patio doors. The BS and WHO guidelines recommend a factor of -15dBA. The appellant’s reduction of 13dBA is to be preferred. With the school operating at full capacity, on the appellant’s figures, the recommended internal noise levels would be exceeded by 4-9dBA on a 1 hour average or 3dBA using a 16 hour average. [6.3.11, 6.3.15, 7.3.3]
12.3.9 Developments operating in day time working hours should not be expected to conform to night time guidelines, even in known instances of shift workers residing nearby. On the other hand, given the nature of the noise from pupils playing outdoors, the 16 hour period is not appropriate because the character of the noise from the school, which is and will be different from the normal diurnal fluctuations in external noise used in the guidelines, which goes on to suggest 1 hour as an example. [6.3.9, 7.3.4, 8.3.5, 9.8.2]
12.3.10 With these factors in mind, residents most likely to be affected by the school could experience close to a doubling of the recommended internal noise levels1. It was agreed that the LAmax levels arising from playground noise would remain approximately the same with the pupil number rising to the expected 840. However, as confirmed by the term time schedule, the frequency of such events would increase. [6.3.1, 6.3.18, 9.6.8].”
23.	The footnote to IR 12.3.10 noted the effect of the use of a logarithmic scale
“The consultants agreed that +10 dB is the equivalent of doubling noise levels”.
24.	With regard to the impact on external noise, the Inspector also concluded that the impacts would be unacceptable:
“12.3.11 Externally, on the appellant’s figures, residents are predicted to experience noise levels of 51dBLAeq16 hour and 57dBLAeq1 hour, which exceed the external guidelines ranges of 50-55dBLAeqT. The WHO guidance even goes as far as recommending levels no higher than 50dBLAeq and 55dBLAeq in outdoor living areas to protect the majority of people from being ‘moderately’ or ‘seriously’ annoyed. While the BS guidance accepts that the values are not achievable in all circumstances, it also goes on to state that the value of 55dBA is regarded as acceptable in noisier environments. Stoke Poges contains pockets of busy areas, even two business parks; but the environment around School Lane and Hockley Lane cannot be described as noisy. The residents refer to it as tranquil and semirural. Ambient noise levels generally reflect those characterisations, and where the 55dBA and above would be out of place. [6.3.14, 7.3.5, 8.3.2, 8.3.4, 9.6.1, 9.8.1, 9.12.1]
12.3.12 From the evidence of people who actually live close to the school, the noise from just 90 pupils is bordering on the ‘seriously’ annoying. Residents describe the noise levels as noticeable and disruptive now. Whether that is the case or opposition to the Academy has generated these responses is difficult to say, given the paucity of complaints to the Council prior to March 2014. However, the objective analysis also shows that the levels are on the fringes of acceptability or below it. Either way, the empirical evidence of those living close to the school cannot be ignored. [6.3.3, 6.3.4, 7.3.6, 9.2.8, 9.2.9, 9.6.2-9.6.4, 9.6.6, 9.6.7, 9.8.2, 9.10.4, 9.11.5, 9.10.6]
12.3.13 Schools are often located in residential areas. But in the case of the appeal site the proximity of neighbouring properties to areas of the school where much of the outdoor activities would take place (with as many as 400-600 pupils concentrated in those areas) gives exceptional cause for concern. [6.3.2] 
12.3.14 Neighbours describe how they are currently unable to use their gardens or live normal lives in their homes when even small groups of pupils play outdoors, even though the measured LAeq1hour level is 47dBA and below the recommended for outdoors. Their homes are close to the play areas concerned, and the way they use their homes is affected during periods that pupils are outdoors, often up to four hours during the school day. The character and range of noises experienced are intrusive and disruptive. That situation occurs with just 90 pupils attending the school. As the Academy reaches full capacity the numbers of pupils using the play areas would increase. Although not all 840 pupils would be outdoors at any given time, the frequency of the current LAmax levels would increase, and add to the current adverse impacts experienced by residents. [7.3.6, 8.3.8, 9.2.8, 9.2.9, 9.6.2-9.6.4, 9.6.6, 9.6.7, 9.8.2, 9.10.4, 9.11.5, 9.10.6]”
25.	The Inspector then considered the proposed acoustic fencing which she rejected as a satisfactory means of mitigation and the Noise Management Strategy which would have some benefits (e.g. by preventing weekend and evening use of the outdoor areas of the school) but not sufficient to remove her concerns.
26.	The Inspector did not consider that the existing permitted use of the appeal site as offices provided a basis for discounting the school noise, nor was she impressed by the limitations on the occurrence of the likely noise concluding that there would “a perceivable change in the acoustic character of the area” caused by the school:
“12.3.17 Fully occupied offices would bring with it the movement of cars entering and leaving the premises 7 days a week. The Academy would similarly generate noise from cars and coaches entering, manoeuvring and leaving the site, albeit during weekdays only. The fact that the premises would be used for 39 weeks of the year does not diminish the magnitude of the impacts experienced by local residents during those 39 weeks. There would be a perceivable change in the acoustic character of the area, residents would avoid using their gardens during the day (as outdoor activities are likely to spread over much of the school day) and are highly likely to materially change the way they use their homes. In other words, they would be exposed to levels crossing the significant observed adverse effects category. [6.3.6, 6.3.8, 6.3.16, 8.3.8]”
27.	Having rejected at IR 12.3.18 the proposed close working between the school and the local community as a likely solution to the noise issues, the Inspector concluded on noise:
“12.3.19 The significant adverse impact on the neighbours’ quality of life that would occur needs to be balanced against three factors: benefits of the school, the Government’s commitment to state-funded schools and the presumption in favour of such facilities applied in the NPPF. The number of homes affected is small. As recognised in the NPPG, decisions must be made taking account of the economic and social benefit of the activity causing the noise, but it is undesirable for exposure above significant observed adverse effects levels to be caused. The appeal proposal falls into the undesirable category for the reasons explained. It would make the homes affected unsatisfactory places to live in. [6.3.19, 7.3.6, 8.3.10]”
28.	In conclusion at IR13.1.1 the Inspector found:
“13.1.1 In terms of its impact on highways and transport, I have concluded that the proposal for prior approval would be acceptable. The evidence of the most up to date and reliable traffic surveys, the predicted trip generation, likely modal split and junction assessments demonstrate that the residual impact of the proposal would not lead to severe conditions. The evidence of contamination risks on the site also do not point to a rejection of the scheme. However, the analysis of existing and predicted noise levels, alongside residents’ experience of the school, leads me to conclude that their living conditions would be materially harmed as the school develops to its full complement. The mitigation measures put forward would do little to alter that position. On the balance of considerations, the appeal should be rejected for the severity of impact on local residents from noise generated by the school.”
29.	As a result, at IR 13.2.1 the Inspector recorded her formal recommendation that prior approval for change of use of the existing office space (Class B1) into a state funded school (Class D1) be refused.
The Decision Letter
30.	The Secretary of State did not accept the Inspector’s recommendation.
1.	In agreement with the Inspector’s approach, DL 7 and 8 stated:
“7. The Secretary of State agrees with the Inspector (IR5.1 and IR12.1.2-12.1.3) that, in considering this appeal, they are both restricted to consideration of those matters related to the acceptability of a prior approval scheme under Class T(1)(b) of the GPDO, namely: (i) transport and highways impacts; (ii) noise impacts; and (iii) contamination risks on the site. Furthermore, the Secretary of State agrees with the Inspector at IR12.1.4 that, because this appeal does not involve an application for planning permission, section 38(6) of the Planning and Compensation Act 2004 is not engaged so that the appeal scheme is not required to be determined in accordance with the development plan.
8. The Secretary of State has also had regard to BS 8233:2014: Guidance on sound insulation and noise reduction for buildings; and to the WHO Guidelines for Community Noise.”
31.	At DL 11 to 13 the Secretary of State agreed with the Inspector that:
i)	the earlier noise conditions were unenforceable;
ii)	the issue particularly concerned impact on local residents for the reasons described at IR12.3.3-12.3.4 (above); 
iii)	“the starting point for assessing the impact on those neighbours has to be an objective assessment of the predicted noise levels against published guidance” (see IR12.3.6 above); and
iv)	the impact of the proposals on internal space where windows etc were closed was acceptable as set out at IR12.3.7.
32.	However, with stated exceptions, the Secretary of State departed from the Inspector’s approach for the reasons set out in DL14-25 and 31-33. He dealt firstly with internal noise levels:
“14. However the Secretary of State notes that the thresholds in the relevant guidance are guideline values only and that there are no European or National noise limits which have to be met. In addition the BS8233 guidance allows a 5dBA relaxation (Note 7, paragraph 7.7.2 of BS8233) such that the internal target levels may be relaxed by 5dBA and reasonable internal conditions still achieved. This relaxation means that the predicted noise levels would meet the criteria for dining rooms and be only marginally above the BS8233 criteria of ‘moderate’ annoyance for living rooms and (daytime resting) in bedrooms, if the 9dB increase were to be applied.
15. The Secretary of State notes that the noise statement of common ground agreed that 8dBA would be the appropriate increase of noise for 600 pupils (IR6.3.13). The Inspector noted that not all pupils will be outside at any one time (IR12.3.14) and in the report considers a maximum number of 600 pupils when assessing external noise levels, during the 20 minute morning break (IR12.3.4). The Secretary of State considers that the likelihood of 840 pupils being outside at any one time would not be usual and that the more accurate maximum is 600 pupils. The Secretary of State therefore considers that the 8dBA increase is to be applied, which further lowers the levels of internal noise experienced to only marginally above the BS8233 criteria of ‘moderate annoyance’.
16. The Secretary of State has also taken into account the inspector’s analysis that the 1 hour period for assessing noise is appropriate because of the character of the noise from the school (IR12.3.9). Whilst the Secretary of State accepts that it was appropriate to adopt the one hour period, it does highlight that the higher noise levels will only be present for limited periods throughout the day, during periods of increased activity. This was indicated at the inquiry to be limited to early in the morning, mid-morning Break, and lunch-time, with only the morning-break period expected to result in the maximum 600 pupils being outside (IR 12.3.4).
17. The Secretary of State also notes that these occurrences would only occur during the 39 weeks of term-time and would not be present for the remaining 13 weeks of the year.
18. The Secretary of State considers it important to recognise that ambient noise levels can fluctuate over a short space of time for a number of reasons unrelated to children’s play.
19. For these reasons the Secretary of State therefore gives only limited weight to the impact of internal noise on local residents.”
33.	The Secretary of State then considered the issue of external noise:
“20. Turning to external noise levels (IR12.3.11), the Secretary of State agrees with the Inspector that, having regard to the fact that ambient noise levels generally reflect the tranquil and semi-rural nature of the area, noise levels of 55dBA and above could potentially be out of place. However the Secretary of State considers it important to note that these are guideline values only. Additionally, as set out at paragraph 15 above, the Secretary of State considers that the 8dBA increase is an appropriate increase of noise given the number of pupils that would be outside at any one period of the day. The Secretary of State notes that the current external noise levels are 47dBA (IR12.3.14) and that, when combined with an 8dBA increase would mean the maximum external noise levels would be 55dBA. The Secretary of State notes that the WHO guidance, at paragraph 4.3.1, provides that external noise should not exceed 55 dBA to prevent serious annoyance. The Secretary of State therefore considers that the external noise levels would remain within the relevant guidelines for noise limits, to which he attaches substantial weight.
21. The Secretary of State has taken account both of the Inspector’s comments at IR12.3.12-12.3.14 about the impact of the noise on the lives of those in the neighbouring properties and of the representations submitted in response to his letter of 9 April 2015, he gives substantial weight to the impact of such an increase.
22. However for the reasons set out above, including those at paragraphs 15 and 16 above, the Secretary of State does not consider that there is sufficient evidence to demonstrate that the noise levels predicted to be generated by the appeal scheme would diminish the occupants’ living conditions so as to expose them to seriously annoying levels of noise giving rise to significant observed adverse impacts to health and quality of life.
23. The Secretary of State notes and agrees with the Inspector’s conclusions at 12.5.2 that some levels of attenuation would be provided by the noise management strategy to which he gives limited weight. The Secretary of State has not considered the acoustic fencing as part of this assessment given that no certainty can be given that the necessary planning consent would be obtained.
24. The Secretary of State agrees with the Inspector (IR12.3.17) that, although the appeal scheme would generate noise from cars and coaches for a shorter period of the year than would fully occupied offices, this does not diminish the magnitude of the impacts experienced by local residents during that period of 39 weeks. Nevertheless, on the basis of the objective evidence presented to him, he does not agree that this could be expected to be sufficient to lead residents to materially change the way they use their homes.
25. Following from his conclusions in the previous paragraphs, the Secretary of State disagrees with the Inspector’s conclusions as he disagrees with her conclusion that the appeal proposal would cause exposure to noise giving rise to significant adverse impacts on health and quality of life.”
34.	In conclusion:
“31. In relation to noise impacts, the Secretary of State concludes that predicted external levels of noise would be acceptable with regard to the relevant guidelines for the reasons set out at above.
32. The Secretary of State notes that the internal noise levels relate to moderate annoyance rather than serious annoyance. The Secretary of State therefore considers that, given that the levels of noise are at the margins of those recommended guidelines, the internal noise levels would not give rise to significant adverse impacts to health and quality of life. The Secretary of State therefore considers the levels of internal noise to be acceptable.
33. The Secretary of State has taken account of the fact that the residents’ experience of the school has led them, and the Inspector, to conclude, that their living conditions would be materially harmed as the school develops to its full potential, but he does not consider that the predicted measurements when considered alongside the relevant guidelines support those conclusions. Overall, therefore, he considers that the appeal proposals satisfy the requirements for granting prior approval.”
35.	The formal decision, which also applied a noise boundary condition to plant and machinery, was therefore:
“34. Accordingly, for the reasons given above, the Secretary of State hereby allows your client’s appeal and grants prior approval for permitted development under Part 3, Class T of the GPDO, for the change of use of existing office space (Class B1) into a state funded school (Class D1) at Pioneer House, Hollybush Hill, Stoke Poges, South Buckinghamshire, SL2 4QP, in accordance with application Ref: 13/01947/KNOT, dated 18 November 2013…”
Applicable legal principles
36.	I do not need to repeat the well-established principles of law which apply to the consideration of decision letters and whether they reveal an error of law. See for example the distillation of the applicable principles by Lindblom J. (as he then was) in Bloor Homes East Midlands Ltd v Secretary of State [2014] EWHC 754 (Admin) at [19] (enlarged by Gilbart J. in South Oxfordshire DC v Secretary of State [2016] EWHC 1173 (Admin) at [86]) and (as he then was) Sullivan J.’s statement of the approach to s. 288 challenges in Newsmith Stainless Ltd v Secretary of State [2001] EWHC Admin 74 at [6]-[8].
37.	Since this case concerns a dispute over technical evidence in the context of specialist guidance, it is necessary to recall that the judicial reluctance to interfere on what are matters of judgment is reinforced. As Holgate J. observed in R. (Nicholson) v Allerdale BC [2015] EWHC 2510 (Admin) at [60] -
“60 Plainly an application for judicial review is not a forum for resolving issues between the parties on technical matters such as the assessment of existing levels of noise in the community or the noise that would be emitted from [the proposed development] when in use, and the means by which that noise should be controlled. These are matters of judgment for the local planning authority.”
38.	This echoes the approach of Carnwath J. (as he then was) in British Aerospace Plc v Secretary of State (1998) 75 P & CR 486 at pp. 497-8:
“I have considerable sympathy with Mr Taylor's general point, and his comments on the individual points I have mentioned. Given the time and expense on technical noise evidence, which attempted to follow the guidance in PPG 24 and other official advice, it is unsatisfactory that at the end of the day it is not clear how the conclusions of the Secretaries of State relate to that guidance or to the technical evidence based on it. 
Mr Taylor's difficulty however, is to convert this into a point of law, or to show that it would have affected the ultimate decision. It is clear that as a matter of law, the Secretaries of State and the Inspector were entitled to reach their own conclusions on the noise issue, even though that might conflict with the technical evidence before them. It seems to me highly desirable, as a matter of policy and practice, that the Inspector and the Secretaries of State should follow the framework established by the technical guidance and evidence. But I know of no principle of law which says that they are bound by that approach. This point was forcibly expressed by Forbes J in Westminster Renslade Ltd -v- Secretary of State [1983] 48 P&CR 255, 263…
… Of course, that does not absolve the decision maker from the obligation to state the reasoning adequately, and in so doing to indicate how he or she has had regard to the relevant policy guidance (see e.g. Gransden -v- Secretary of State [1987] 54 P&CR 86.). Points of the kind on which Mr Taylor relies could be relevant to such a challenge if they led to the basis of the overall decision being materially uncertain.” 
39.	The duty to give reasons in planning cases is found in the well-known statement of Lord Brown in South Buckinghamshire DC v Porter (No.2) [2004] 1 WLR 1953 at [36], summarised in Bloor Homes at [19(2)]. I note Lord Brown’s endorsement at [33] of Sir Thomas Bingham MR’s observations in Clarke Homes Ltd v Secretary of State (1993) 66 P & CR 263 at pp 271–272:
“I hope I am not over-simplifying unduly by suggesting that the central issue in this case is whether the decision of the Secretary of State leaves room for genuine as opposed to forensic doubt as to what he has decided and why. This is an issue to be resolved as the parties agree on a straightforward down-to-earth reading of his decision letter without excessive legalism or exegetical sophistication.” 
40.	Where the Secretary of State is disagreeing with his Inspector it is necessary to identify (at a level of detail appropriate to the context) the reasons for the disagreement, a point reinforced by Lewison LJ in Horada v Secretary of State [2016] EWCA Civ 169 at [40] to [41]. Subject to that, however, there can be no doubt that the Secretary of State is entitled to depart from an inspector’s views and recommendations. See Sullivan LJ in Ecotricity (Next Generation) Ltd v Secretary of State [2015] EWCA Civ 657 at [32] to [35] dealing with the issue of visual impact of wind turbines – 
“35. The test posed in all of those cases (which I would endorse) is whether the Secretary of State had sufficient material before him on which he was reasonably able to make a judgment on the issue of visual impact.”
41.	However, it is particularly important where, as here, the issues are highly technical and the parties have all engaged consultants to present their evidence to the Inspector, that it should be recognised (see Lord Brown in Porter (No. 2) at [36]) that the IR and DL are addressed to an informed readership who are well aware of the arguments which have been advanced – especially here where there was not only a hearing before the Inspector but a further round of written representations following quashing of the first decision and prior to the redetermination. In the context of the Lord Chief Justice’s concerns as to intelligibility in Horada at [57] to [59] (in the particular circumstances of compulsory purchase) this is an area of planning which inevitably requires consideration of often difficult technical matters.
42.	Issues arise with respect to the interpretation not only of national policy and guidance in the form of the NPPF and PPG, to which the approach in Tesco Stores Ltd. v Dundee City Council [2012] P.T.S.R. 983 applies (see Bloor Homes at [19(4)]) but also of BS8233 and the WHO Guidelines. While the need for consistency considered by Lord Reed in Tesco at [18] appears applicable to such guidance, the caution he expressed at [19] with respect to not treating development plan policies as akin to contracts or statutes, especially since they contain broad statements of policy which have to be applied to the specific case in the exercise of planning judgment, applies with even greater force to the noise guidance here. The BS is technical guidance for noise experts and the WHO Guidelines are international noise guidance – neither of which was drafted with the same objectives as planning policy nor intended to have the same formal role and effect of development plans.  
43.	Indeed, the Foreword to the WHO document itself highlights the dangers of taking a formalistic approach to its meaning in that it describes the process undertaken and the nature of the document which places it at some considerable remove from the planning policy considered in Tesco:
“The scope of WHO’s effort to derive guidelines for community noise is to consolidate actual scientific knowledge on the health impacts of community noise and to provide guidance to environmental health authorities and professionals trying to protect people from the harmful effects of noise in non-industrial environments. … At a WHO/EURO Task Force Meeting in Düsseldorf, Germany, in 1992, the health criteria and guideline values were revised and it was agreed upon updated guidelines in consensus. The essentials of the deliberations of the Task Force were published by Stockholm University and Karolinska Institute in 1995. In a recent Expert Task Force Meeting convened in April 1999 in London, United Kingdom, the Guidelines for Community Noise were extended to provide global coverage and applicability, and the issues of noise assessment and control were addressed in more detail. This document is the outcome of the consensus deliberations of the WHO Expert Task Force.”
44.	In my judgment, the Court should be particularly wary of approaching such documents legalistically and should treat them broadly as documents produced by organisations seeking to offer technical advice and guidance. Moreover, in the context of national policy they are not treated as setting any specific noise standards (see the NPSE, above) and they are clearly matters for the judgment of the planning decision-maker (see BAE Plc). While it is necessary to understand them sufficiently to enable them to be taken into account correctly (see EC Gransden & Co Ltd v Secretary of State (1987) 54 P & CR 86) in my judgment more leeway should be given to the decision-maker with regard to their meaning and application than would be the case with planning or other policy.
The Grounds of Challenge
45.	Although Mr Williams for SPPC and Mr Lopez for SBDC advanced separate grounds of challenge, Mr Lopez was content for me to take the SBDC grounds on the basis formulated by Mr Williams:
i)	The First Defendant failed properly to interpret and apply the noise guidance to which he referred (WHO and BS8233) and as such he failed to take into account material considerations;
ii)	The First Defendant failed to apply properly paragraph 123 of the NPPF in light of the PPG;
iii)	The First Defendant acted irrationally in disagreeing with the conclusions of the Inspector in relation to the technical noise evidence; and
iv)	The First Defendant failed to give adequate reasons for his decision such that it is not possible to know whether the First Defendant applied policy and guidance properly in reaching his decision and thus caused the Claimant substantial prejudice.
46.	I will not attempt to set out the considerable detail of these grounds advanced in writing in SPPC’s Skeleton Argument and note that greater clarity might have been achieved by a more succinct statement of the argument. Not all the points in the skeleton were pursued before me, e.g. the issue of the increase in levels due to a maximum of 600 pupils being outside at once. While the issues do require careful explanation, the fact that it took SPPC some 55 (often lengthy) paragraphs to set out just Grounds 1 and 2 underlines the need for caution expressed in the authorities with respect to challenges on grounds of technical judgment. This is especially so where, as here, the issues relate to the assessment of noise and the application of guidance outside the scope of planning policy in order to answer the apparently (perhaps deceptively) simple question posed in para. 123 NPPF as to whether there are “significant adverse impacts on health and quality of life”.
47.	Mr Whale for the First Defendant and Mr Maurici QC for the SSE, robustly defended the First Defendant’s decision. I will deal with their submissions as necessary while considering the grounds below.
Ground 1 – misinterpretation of guidance
48.	This ground breaks down into the following points, namely the following main errors alleged to be contained within the DL:
i)	The application of a threshold guideline of “moderate annoyance” by reference to BS 8233 when the BS did not contain such a guideline;
ii)	The failure to note that the key impact value in the WHO, reflected in the BS, was 35 dB for internal living areas;
iii)	The allowance of “up to 5 dB” permitted by Note 7 to para. 7.7.2 and Table 4 of the BS neither changed the threshold nor meant that the threshold value of 35 dB LAeq should be ignored when what was proposed amounted to an increase of 8 dB, almost a doubling of noise levels (given the logarithmic scale applicable to LAeq noise assessment);
iv)	The 50 and 55 dB guidelines in the WHO are not thresholds of acceptability for external noise;
v)	The DL did not consider the character of the noise nor the implications of the change in noise levels of +8 or +9 dB for the acoustic character of the area (and thus its implications for local residents in their homes), in contrast to IR 12.3.13-12.3.14, 12.3.17 and 12.3.19. This should have been considered in the context of the PPG and NPSE;
vi)	The DL’s conclusion that the noise levels “would remain within the relevant guidelines” (DL 20) was thus based on a misinterpretation of the guidelines.
49.	In order to found his case on Ground 1, Mr Williams relies heavily on the terms of the WHO Guidance and BS8233 and submits that the key threshold value for noise impact with respect to internal noise is the 35dB referred to in the BS at Table 4 indoor ambient noise levels for dwellings (resting, living room or daytime resting in a bedroom) which are said in Note 2 to derive from the WHO. 35dB appears in WHO Table 4.1 Guideline values for community noise in specific environments under “Dwelling, indoors” with the critical heath effects listed as “speech intelligibility and moderate annoyance, daytime and evening”. He submits that the First Defendant erred in taking 40 dB as the threshold and in failing to recognise the correct WHO standard.
Time index for assessment
50.	The WHO Guidelines (see section 4.4.), as for the BS, take threshold values by reference to a LAeq determined by reference to a time index of 16 hours, whereas here the Inspector determined (above) that in the circumstances it was appropriate to take a 1 hour LAeq instead, given the intermittent and limited nature of the noise. The BS at Note 2, though not the WHO, suggests that in some cases a different time period might be taken:
“In cases where local conditions do not follow a typical diurnal pattern, for example on a road serving a port with high levels of traffic at certain times of the night, an appropriate alternative period, e.g. 1 hour, may be used, but the level should be selected to ensure consistency with the levels recommended in Table 4.”
The Inspector accepted the use of the 1 hour period at IR 12.3.9.
51.	The experts did not adjust the levels for the different period used though it was clear from Mr Jarman’s noise report for SSE and the SSE’s submissions (see IR 6.3.14 and 6.3.15) that different results would flow from the use of different time periods. See Mr Jarman’s Tables T5 and T6 and para. 5.31 (Bundle pp. 413-414). For example, projected playground noise levels in T6 are 51 dB on a 16 hour LAeq whereas they are 57 dB on a 1 hour basis. This choice of index periods was noted by the First Defendant at DL16 and accepted but with the qualification that it highlighted that the higher noise levels would “only be present for limited periods throughout the day”.  That view was also advanced by Mr Jarman for SSE in paragraph 5.21 of his Report (see also IR 6.3.16). I cannot see how that judgment of the First Defendant can be faulted.
The WHO Guidance
52.	The WHO guidance however is not simply Table 4.1 but Section 4 itself which provides the discussion under the heading Guideline Values. 4.4 states:
“The WHO guideline values in Table 4.1 are organized according to specific environments. When multiple adverse health effects are identified for a given environment, the guideline values are set at the level of the lowest adverse health effect (the critical health effect). An adverse health effect of noise refers to any temporary or long-term deterioration in physical, psychological or social functioning that is associated with noise exposure. The guideline values represent the sound pressure levels that affect the most exposed receiver in the listed environment. … 
The different critical health effects are relevant to specific environments, and guideline values for community noise are proposed for each environment.”
53.	In Section 4.3 Specific Environments 4.3.1 deals with dwellings. However, there is no mention in that subsection of the 35 dB value although critical effects of noise are said to be “sleep, annoyance and speech interference”. What 4.3.1. does say (other than in relation to night time noise and sleep disturbance) relates to exterior noise:
“To protect the majority of people from being seriously annoyed during the daytime, the sound pressure level on balconies, terraces and outdoor living areas should not exceed 55 dB LAeq for a steady, continuous noise. To protect the majority of people from being moderately annoyed during the daytime, the outdoor sound pressure level should not exceed 50 dB LAeq. These values are based on annoyance studies, but most countries in Europe have adopted 40 dB LAeq as the maximum allowable level for new developments (Gottlob 1995). Indeed, the lower value should be considered the maximum allowable sound pressure level for all new developments whenever feasible.”
54.	35 dB is referred to under 4.2 Specific Effects at 4.2.1 Interference with communication – where it is stated:
“It is usually possible to express the relationship between noise levels and speech intelligibility in a single diagram, based on the following assumptions and empirical observations, and for speaker-to-listener distance of about 1 m:
a. Speech in relaxed conversation is 100% intelligible in background noise levels of about 35 dBA, and can be understood fairly well in background levels of 45 dBA.
b. Speech with more vocal effort can be understood when the background sound pressure level is about 65 dBA.
…
Speech signal perception is of paramount importance, for example, in classrooms or conference rooms. To ensure any speech communication, the signal-to-noise relationship should exceed zero dB. But when listening to complicated messages (at school, listening to foreign languages, telephone conversation) the signal-to-noise ratio should be at least 15 dB. With a voice level of 50 dBA (at 1 m distance this corresponds on average to a casual voice level in both women and men), the background level should not exceed 35 dBA. This means that in classrooms, for example, one should strive for as low background levels as possible. This is particularly true when listeners with impaired hearing are involved, for example, in homes for the elderly.”
55.	However, in terms of annoyance, the matter is explained differently contrasting it with questions of speech intelligibility. In Section 4.1 Introduction it is stated:
“In the following, guideline values are summarized with regard to specific environments and effects. For each environment and situation, the guideline values take into consideration the identified health effects and are set, based on the lowest levels of noise that affect health (critical health effect). Guideline values typically correspond to the lowest effect level for general populations, such as those for indoor speech intelligibility. By contrast, guideline values for annoyance have been set at 50 or 55 dBA, representing daytime levels below which a majority of the adult population will be protected from becoming moderately or seriously annoyed, respectively.”
56.	This is repeated under 4.2.7 Annoyance responses:
“The annoyance response to noise is affected by several factors, including the equivalent sound pressure level and the highest sound pressure level of the noise, the number of such events, and the time of day. ...
Annoyance to community noise varies with the type of activity producing the noise. Speech communication, relaxation, listening to radio and TV are all examples of noise-producing activities. During the daytime, few people are seriously annoyed by activities with LAeq levels below 55 dB; or moderately annoyed with LAeq levels below 50 dB.”
57.	The Executive Summary puts the issues slightly differently under 4 Guideline values:
“When listening to complicated messages (at school, foreign languages, telephone conversation) the signal-to-noise ratio should be at least 15 dB with a voice level of 50 dB(A). This sound level corresponds on average to a casual voice level in both women and men at 1 m distance. Consequently, for clear speech perception the background noise level should not exceed 35 dB(A). In classrooms or conference rooms, where speech perception is of paramount importance, or for sensitive groups, background noise levels should be as low as possible.”
And -
“The capacity of a noise to induce annoyance depends upon its physical characteristics, including the sound pressure level, spectral characteristics and variations of these properties with time. During daytime, few people are highly annoyed at LAeq levels below 55 dB(A), and few are moderately annoyed at LAeq levels below 50 dB(A).”
58.	Accordingly, it appears from the WHO Guidelines that Table 4.1 is not as clear in its guidance as might be thought since the 35 dB level is related to speech intelligibility and the general levels of noise likely to cause moderate or serious/high annoyance are related to the 50 dB and 55dB values. While 4.3.1 relates those values to the outdoor spaces of dwellings it does not deal with interior daytime levels and there are general statements in the Executive Summary, and Sections 4.1 and 4.2.7 which relate those to levels of annoyance generally.
59.	To put these levels into context, I note that Mr Ellis for SBDC reproduced in his Report at para. 2.2.5 a table of sound levels from typical noise sources (using A-weighted sound levels, which are also the basis of LAeqs) from which it can be seen that 30 dB represents the noise environment of a library, bedroom at night or quiet rural night-time, 50 dB represents the level of light traffic noise at 30m in a large office or quiet urban daytime and 60 dB at 1.5m represents the level of ordinary conversation e.g. in a store.
60.	These considerations highlight the need for the Court to approach the interpretation and application of the WHO document with caution. They also underline the fact that the approach to this guidance must turn a great deal on the judgment of the decision-maker and a consideration of the circumstances of the specific case. Having regard to the above matters, I do not consider that it could be said that the Secretary of State acted unlawfully in taking 50 and 55 dB one-hour LAeqs as thresholds relating to annoyance.
BS8233:2014 guidance
61.	BS8233 guidance at Section 7.7 Table 4 simply treats the WHO guidance in Table 4.1 at face value, which may not be accurate, but in any event sets 35 dB as its own internal living room standard for ambient noise levels, with a 40 dB level for dining rooms which is not present in WHO Table 4.1. It is perhaps therefore understandable that, given the different issues addressed by the WHO Guidance, Note 7 (Table 4 and para. 7.7.2) to the BS qualifies all of its the indoor ambient noise level values:
“Where development is considered necessary or desirable, despite external noise levels above WHO guidelines, the internal target levels may be relaxed by up to 5 dB and reasonable internal conditions still achieved.”
62.	With regard to external levels, BS8233 at 7.7.3.2 states:
“For traditional external areas that are used for amenity space, such as gardens and patios, it is desirable that the external noise level does not exceed 50 dB LAeq,T, with an upper guideline value of 55 dB LAeq,T which would be acceptable in noisier environments. However, it is also recognized that these guideline values are not achievable in all circumstances where development might be desirable. In higher noise areas, such as city centres or urban areas adjoining the strategic transport network, a compromise between elevated noise levels and other factors, such as the convenience of living in these locations or making efficient use of land resources to ensure development needs can be met, might be warranted. In such a situation, development should be designed to achieve the lowest practicable levels in these external amenity spaces, but should not be prohibited.”
Consideration of Ground 1
63.	Mr Williams pointed out that the BS does not refer to any criterion for annoyance still less “moderate annoyance” contrary to DL 14.
64.	Mr Williams criticised the use of 40 dB by means of the relaxation of 5 dB in BS Note 7 and then using it to test the predicted level of internal noise as an exceedance of only 2 or 3 dB. He submitted that the Note 7 adjustment could not alter the threshold value and in any event the predicted level represented an 8 dB increase over the threshold, almost a doubling of noise (+10 dB being a doubling of noise levels).
65.	There was an issue as to whether the SOCG required an 8 dB or 9 dB adjustment for internal noise with windows open but Mr Williams sensibly did not pursue that in the light of lack of clarity in the SOCG and the SSE’s maintaining at the hearing and subsequently that an increase of 8 dB was appropriate for the maximum number of 600 pupils likely to be outside even when the school reached a total of 840 pupils (see IR 6.3.13, 12.3.4 and 12.3.13).
66.	Whilst it is true that 35 dB was used as the starting point by Mr Jarman for his 4-9 dB increases (depending on the threshold value taken) at e.g. paragraph 5.21 the SSE still contended that internal target levels could be relaxed by up to  5 dB as recorded at IR 6.3.17:
“The BS expressly allows for relaxing internal target levels by up to 5dBA where development is considered desirable. The changes to the GPDO to allow school use underline the importance and desirability of such development.”
67.	Taking the broad approach to issues of interpretation of noise guidance and matters of judgment, whilst I can understand the Claimants’ concerns, I do not consider that there has been an error of law.
68.	First, the relaxation of 5 dB was supported by the SSE’s case and, as Mr Maurici pointed out, there was no issue whether the relaxation should be for less than 5 dB – it was an “all or nothing” question. I do not think in the context the First Defendant needed to do anything more than to signal to the parties that he had accepted the SSE’s case and allowed the relaxation given that the SSE had advanced a case based on desirability of the development.
69.	Secondly, the issue of the base threshold of 35 dB has been overstated. I have already examined the WHO guidance and noted the specific role of 35 dB and also the flexibility allowed by BS8233. It cannot seriously be contended against the background of the evidence, the detail set out in the IR (both in the summaries of the parties’ cases and in the Inspector’s conclusions), the known threshold values and the fact that the First Defendant at DL 8 noted that he had specifically had regard to BS8233 and the WHO Guidelines that the First Defendant was not aware of the 35 dB threshold. Indeed, the very use of the relaxation referred to in DL14 begs the question “relaxation of what?” To which the answer must be the internal threshold levels in BS8233 which includes the 35 dB level. 
70.	Indeed, DL14 makes it clear in terms that it is a relaxation of the internal target levels which must be a reference to the 35 dB and 40 dB levels in Table 4. It seems to me that it was open to the Secretary of State to read Note 7’s “the internal target levels may be relaxed by up to 5 dB and reasonable internal conditions still achieved” as meaning just that i.e. the internal target levels could be adjusted. As Mr Whale submitted, it is the target level that is adjusted, which is reflected in DL14 and which to my mind permits the decision-maker to adopt a higher threshold value and not to apply both the base and adjusted thresholds as Mr Williams urged should have been done. On that basis, I consider that it was within the First Defendant’s reasonable judgment to conclude that the criterion for the dining room would be met and that the predicted levels would “be only marginally above” the criterion for living rooms and daytime use of bedrooms. On the assumption of a 9 dB increase, the exceedance would be 3 dB and on the 8 dB increase (for the 600 pupils maximum), it would be 2 dB. Mr Jarman’s Report at 5.20 stated that a 3 dB excess was “small”. The final judgment of the significance of the extent to which the threshold is exceeded was plainly a matter for the decision-maker. I also agree with Mr Maurici’s submission that BS8233 clearly says that the 5 dB relaxation can be applied and still result in “reasonable conditions” and that there is nothing unlawful in that approach.
71.	The First Defendant was plainly aware of the fact that the increase was one of 8 or 9 dB, since he specifically referred to it in DL 14 and DL 15. Whilst Mr Williams urged on me that this amounted to almost a doubling of the noise levels, I note that both the WHO and BS provide guidance in this context not by reference to the extent of the increase in noise pressure levels but by reference to specific levels. They must therefore contemplate that noise levels could increase above those currently experienced (possibly substantially) and still be acceptable in terms of the guideline levels.
72.	Whilst Mr Williams is correct that BS8233 does not have a criterion of “moderate annoyance” I do not consider that the criticism succeeds in establishing an error of law. The use of that phrase does not detract from the fact that at DL 14 (and thus DL 32) the First Defendant is clearly referring to the adjusted threshold level in BS8233. Moreover, the phrase is used in the WHO to refer to the critical effects in connection with daytime guideline value for “dwelling, indoors”, which may be adjusted under the BS applying Note 7. Indeed, the issue of annoyance is otherwise considered by the WHO Guidelines in the context of 50 and 55 dB levels. As Mr Whale submitted, this may be no more than a “labelling” issue rather than a legal one. I do not consider that the incorrect use of terminology with regard to the BS is misleading to anyone, still less to the informed reader such as the Claimants.
73.	With regard to the Claimants’ criticisms regarding external noise issues, the main contentions appear to be that the 50 and 55 dB levels were misinterpreted by the First Defendant to be levels of acceptability, which it is said they were not, and that the 55 dB level was only supported by BS8233 in noisier areas, whereas the locality here was agreed to be tranquil and semi-rural (DL20 and IR 12.3.11). 
74.	I have already set out at some length the provisions of BS8233 and the WHO Guidelines on annoyance. I agree with Mr Maurici’s submission that there was a sound basis for the First Defendant’s reliance on a guideline of 55 dB. At DL 20 the First Defendant agreed with the Inspector that given the ambient noise levels “noise levels of 55 dBA and above could potentially be out of place” but then properly observed that it was “important to note that these are guideline values only” and applying an 8dB increase (based the maximum of 600 pupils being outside at any one time) “that the external noise levels would remain within the relevant guidelines for noise limits, to which he attaches substantial weight” i.e. not above 55 dB. 
75.	This conclusion is reinforced in my judgment by the fact that, as already noted, the WHO states at 4.2.7 (and elsewhere) that –
“During the daytime, few people are seriously annoyed by activities with LAeq levels below 55 dB; or moderately annoyed with LAeq levels below 50 dB.” 
76.	I do not therefore agree with Mr Williams that it was not open to the First Defendant to have regard to the 55 dB level as a general limit in the light of the WHO Guidelines.
77.	Further reinforcement is provided by SBDC’s noise consultant Mr Ellis who adopted the 55 dB threshold himself as the appropriate threshold at p. 12 of his Report (Bundle p. 488) and he confirmed this at the hearing as was pointed out at para. 1(6) of the SSE/GLD letter to the First Defendant in response to SPPC’s letter of 9 June 2015 (Bundle p. 161).
78.	Mr Williams pointed out that the NPSE applies the NOEL/LOAEL/SOAEL terminology and in the case of the latter refers to it as “the level above which significant adverse effects on health and quality of life occur” (NPSE, paras. 2.19-2.22). He also draws attention to the fact that the PPG (using the web-based reference ID 30-005-20140306) provides guidance on How to recognise when noise could be a concern which refers to behavioural changes when noise exposure is increased and how the noise exposure hierarchy should be approached. The table refers to “affects the acoustic character of the area such that there is a perceived change in the quality of life” as Observed Adverse Effect – Noticeable and Intrusive. Under Significant Observed Adverse Effect - Noticeable and Disruptive – the PPG table refers to “The noise causes a material change in behaviour and/or attitude e.g. avoiding certain activities during periods of intrusion” (such as keeping windows closed) and “Quality of life diminished due to change in acoustic character of the area”. 
79.	As I have already mentioned, the policy guidance provides no specific levels or thresholds and the NPSE notes the absence of any national or European noise limit which has to be met. The qualitative categorisation employed by the NPSE and PPG all turns on the conclusions reached by the decision-maker as to the assessed impacts of the noise. It does not provide guidance as to when those impacts will occur but only how those impacts should be categorised once they have been ascertained. Their role here is therefore only in reaching a conclusion as to the NPPF para. 123 test and they do not provide real assistance in assessing the extent and nature of the impacts themselves.
80.	However, the guidance does require the decision-maker to consider the implications of changes in noise level on the character of the area and the quality of life of local residents and Mr Williams was at pains to point out the contrast between the detailed consideration of these issues at IR 12.3.13, 12.3.14, 12.3.17 and 12.3.19 and the DL. The Inspector, whilst noting that the incident of complaints with the existing use of the appeal premises by 90 pupils appeared to coincide with the making of the prior approval applications (IR 12.3.12) nonetheless attached significance to the evidence of local residents as to the difficulties they already experienced from the use of the school “even when small groups of pupils play outdoors” (IR.3.14). That evidence was summarised by her at Section 9 of the IR and together with her consideration of the predicted noise levels led to her conclusion that the acoustic character of the area would be changed and it would materially change the way in which residents would use their homes, concluding that “they would be exposed to levels crossing the significant observed adverse effects category” (IR 12.3.17) and “would make the homes affected unsatisfactory places to live in” (IR 12.3.19).
81.	Whilst the First Defendant did not go into the same detail as the Inspector’s recommendations in IR Section 12.3 nonetheless it is sufficiently clear that he did have regard to the issue of character and to the effect which the proposals would have on the use of residents’ homes. He did not have to refer expressly to national guidance in the PPG in order to do so (Bloor Homes at [19(6)]). That the First Defendant did so is sufficiently clear from DL 16 (character of the noise from the school), DL 21 (taken account of the Inspector’s comments at IR 12.3.12 to 12.3.14), 22 (consideration of impact of noise), 24 (whether would lead residents to materially change the use of the homes) and 33 (residents’ experience of the school to date). I do not think that there is anything in the submission that the First Defendant did not have in mind the NPSE and PPG guidance and the terminology he uses in the DL reflects that guidance. I do not see any real tension between the limited weight given at DL 19, the substantial weight given to impact of the increase referred to in DL 21 and the ultimate conclusion that the levels were not such as to justify concluding there was a significance adverse impact to health or quality of life. 
82.	As Mr Whale submitted, the DL shows the First Defendant had regard not only to the guidance but a range of material considerations, including: an objective assessment of the predicted noise levels against published guidance as a starting point (DL 12); the effect of windows and patio doors being open (DL 13); the character of the school noise (DL 16); the periodic nature of higher noise levels (DL 16); the effect of school holidays (DL 17); and fluctuations in ambient noise levels (DL 18). 
83.	I do not consider for the reasons set out above that the First Defendant erred in law at DL 31-33 in concluding that the proposals “would be acceptable with regard to the relevant guidelines” (so far as external noise levels were concerned) and that internally the “noise levels relate to moderate annoyance rather than serious annoyance” so that the First Defendant was entitled to conclude in his judgment that “the levels of noise are at the margins of those recommended guidelines”. 
84.	The Claimants’ case on character and impact, for all Mr Williams’ ingenuity seems to me to come down to the fact that they preferred the Inspector’s conclusions on character and impact to those reached by the Secretary of State which does not disclose an error of law. 
85.	Accordingly, whilst I have considered the elements of Ground 1 in perhaps more detail than was warranted, in the light of the terms of the BAE and Nicholson judgments, I conclude that the First Defendant had ample support for disagreeing with his Inspector, that in doing so he applied his own judgment as he was entitled to do to matters of predicted impact, that he had proper regard to material considerations (including the available guidance) and did not fail to have regard to, misconstrue or misapply the available policy and guidance. Whilst he accepted the concerns of local residents based on their experience of the 90 pupils currently at school (DL 21 and 33) he did not consider it appropriate to go so far as the Inspector and was entitled to disagree with the Inspector on the significance and consequences of the predicted impacts. He did not judge that those predicted impacts fell within the SOAEL category and was entitled to reach the conclusion in DL 22, 25 and 31-33 consistent with para. 123 NPPF that the proposals would not have significant adverse impacts on the health and quality of life of local residents.
86.	I therefore reject Ground 1.
Ground 2 – failure to apply para. 123 NPPF properly
87.	Mr Williams and Mr Lopez complain that in approaching para. 123 NPPF the First Defendant failed to consider and apply the guidance in Section 30 of the PPG (“Noise”). I have already considered this issue in the context of Ground 1 and have explained why I do not consider that there was a failure to consider or apply the PPG. The First Defendant was entitled to conclude in his judgment that the predicted noise impacts would not reach the levels advised by the PPG to be a significant observed adverse effect or a significant adverse impact within para. 123 of the NPPF. I therefore reject this ground of challenge also.
Grounds 3 and 4 – irrationality and reasons
88.	I deal with these together since they are really different aspects of the same complaint. Indeed, I am not convinced that the irrationality challenge adds anything of substance to Grounds 1 and 2 since I have already concluded that the First Defendant was entitled to reach the judgments set out in the DL on the noise issues.
89.	On the challenge to the reasons, I consider that the real complaint is again encapsulated in Grounds 1 and 2 and the reasons for the First Defendant’s decision and thus his disagreement with the Inspector are set out at length in DL 14 to 25 and 31 to 33. This is not a Horada-type case where psychic powers were needed to ascertain the Secretary of State’s reasons for disagreeing with the Inspector. This was a decision setting out detailed reasons for the conclusion reached, addressed to informed parties who were well-aware of the noise issues. Approached in the light of Sir Thomas Bingham MR’s observation in Clarke Homes, above, I do not consider that the DL leaves “genuine as opposed to forensic doubt” as to what the First Defendant has decided and why. The Claimants’ real complaint goes to the substance not the reasons for the decision.
90.	I therefore reject both Grounds 3 and 4.
Conclusions
91.	It appears to me that viewed as a whole the main Grounds 1 and 2 were arguable (although not every aspect of them, e.g. the character issue) and I grant permission to bring the challenges to them under s. 288 TCPA. Since Grounds 3 and 4 are closely tied up with those main grounds and are, as is often the case, alternative ways of formulating the issues, it seems to me that I should adopt the same approach as for the main grounds and grant permission to challenge on Grounds 3 and 4 also.
92.	However, on the substantive issues, I have set out above my conclusions on each of the grounds of challenge and refuse the applications.