CO/4261/2009
Neutral Citation Number: [2009] EWHC 3531 (Admin)
IN THE HIGH COURT OF JUSTICE
QUEEN'S BENCH DIVISION
ADMINISTRATIVE  COURT

Royal Courts of Justice
The Strand
London
WC2A 2LL

Monday  7  December  2009

B e f o r e:

MR  JUSTICE  CRANSTON
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B E T W E E N:

GUILDFORD  BOROUGH  COUNCIL
Claimant
and

SECRETARY OF STATE FOR COMMUNITY AND LOCAL GOVERNMENT
Defendant
and

(1) SIMON  MOFFAT
(2) CARINA MOFFAT
Interested Parties
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Mr Ian Albutt (instructed by Guildford Borough Council)
appeared on behalf of the Claimant

Mr James Strachan (instructed by the Treasury Solicitor)
appeared on behalf of the Defendant
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J U D G M E N T
Monday  7  December  2009

MR JUSTICE CRANSTON:  
Introduction
1.  This is an application under section 288 of the Town and Country Planning Act 1990 ("the 1990 Act").  The claimant, Guildford Borough Council ("Guildford"), seeks to challenge a decision of an Inspector appointed on behalf of the defendant Secretary of State.  That decision allowed an appeal against Guildford's refusal of planning permission of an extension to a dwelling-house located in the Green Belt.

Background
2.  The claim relates to land at Fallows End, Woodhouse Lane, Holmbury St Mary, Dorking, Surrey.  It is a residential property owned and occupied by Mr and Mrs Moffat.

3.  The appeal site forms part of the Woodhouse Lane development, an extensive low-density estate erected principally during the inter-war period.  Mr and Mrs Moffat's house was built at about that time.  It is at the furthermost point of the estate.  The properties are set in spacious plots and the majority have been extended since 1948.  The Moffats' house has been extended on two previous occasions.  Firstly, in 1993 a two-storey rear extension was built to provide a breakfast and television room on the ground floor, and two bedrooms and a bathroom on the first floor above.  Secondly, in 2000 a single storey conservatory at the rear of the property was built.  It is agreed that the original floor area of the house as erected was 149.4 square metres and that the existing floor area is 235.8 square metres.

4.  The site and the surrounding area are within the Green Belt, an Area of Outstanding Natural Beauty and an Area of Great Landscape Value.  The estate lies outside any defined settlement.

5.  On 8 August 2008 Mr and Mrs Moffat applied for planning permission to construct a two-storey extension to their existing house.  The proposal would create an additional 114.1 square metres, representing an increase of 48 per cent over the existing dwelling and an overall increase on the original dwelling of 134 per cent.  It is agreed that this would constitute a two-and-one-third increase over the original dwelling.  Mr and Mrs Moffat's planning application showed the nature of the proposed extension, its effect, and a comparison with the buildings in the surrounding area of the estate.  There was a design and access statement and a planning statement which addressed the issue of whether the extension was an appropriate development for the purposes of Planning Policy Guidance Note 2 Green Belts ("PPG2") and also whether it complied with policy H9 of the Local Plan, Extensions to Dwellings in the Countryside.  They also identified whether other properties in the area had already been subject to permitted extensions over the size of the original dwelling in excess of the Moffats' proposals.

6.  On 8 October 2008, Guildford refused planning permission.  That was for two reasons.  The first was that the proposal would have an adverse impact on the openness of the Green Belt and would result in a disproportionate addition to the original dwelling by virtue of its design, size, bulk and mass (notably its width and the additional floor area).  The application was therefore contrary to PPG2 (Green Belts), and also failed to comply with Policies H9 and RE12 of the Guildford Borough Local Plan 2003 (saved policies) and policy LO4 of the Surrey Structure Plan 2004 (saved policies).  

7.  The second reason for refusal related to the size, design, width, depth and additional floor space of the proposal.  That, in Guildford's view, had an unacceptable impact on the scale and character of the existing dwelling-house, contrary to local policy H9 and the Council's adopted Supplementary Planning Guidance for Residential Extensions 2003.

8.  Mr and Mrs Moffat appealed to the Secretary of State under section 78 of the Town and Country Planning Act 1990 ("the 1990 Act").  An Inspector, Mr Richard Maile, was appointed.  There was a hearing and a site visit on 10 March 2009.  For that hearing the Moffats' appeal statement addressed the relevant policy framework and contained an assessment of the proposal against Guildford's reasons for refusal.  In response to Guildford's position that the extension was disproportionate to the original dwelling, the Moffats submitted evidence of extensions permitted by Guildford for houses on the same estate, and an analysis of the percentage increase in floor area over and above the original dwellings.  For example, for the property "Little Thatch" approval had been given on 15 February 2008 for a 189 per cent increase over the original dwelling; on 15 December 2008 permission had been given by Guildford for an extension of "Over Sutton" which would result in an increase of 121 per cent over the original dwelling; and on 13 October 2006 permission was given for an increase in the size of the property "Oakleigh" for an increase of 209 per cent over the original dwelling.

9.  Guildford's appeal statement referred not only to the percentage increase over the original dwelling, but also to the increase in floor space which the proposal entailed from that of the existing dwelling.  In its summary it contended that the proposed extension would be disproportionate to the original building and also that the two-storey extension of the scale, bulk and height proposed would result "in a large and dominant addition to the dwelling that would detract from the openness of the Green Belt".

10.  In his decision letter dated 25 March 2009 ("the decision letter"), the Inspector allowed the Moffats' appeal.  He granted planning permission, subject to a condition relating to the commencement of the development within three years and to a condition requiring the submission and approval of details and samples of materials to be used in the extension.

11.  In this application, dated 5 May 2009, Guildford challenges the decision on the basis that the Inspector erred in law.  In summary, Guildford contends that the Inspector misdirected himself in respect of PPG2 (Green Belts).  It is submitted that the Inspector did not apply the correct approach to the issue of whether the extension was appropriate development through a comparison of the size of the proposed extension at Fallows End with the size of the original building.  

12.  The defendant Secretary of State rejects that analysis.  In outline he submits that, on a proper and fair reading of the decision letter, it was clear that the Inspector did properly direct himself in respect of the applicable planning policies.

Planning Policies
13.  PPG 2 (Green Belts) sets out the policy guidance which applies throughout the country in relation to Green Belt development.  Paragraph 3.1 provides that there is a general presumption against inappropriate development within the Green Belt and that such development should not be approved except in very special circumstances.  Under paragraph 3.2 that inappropriate development is by definition harmful to the Green Belt.  It is for an applicant to show why permission should be granted.  Very special circumstances to justify inappropriate development will not exist unless the harm by reason of inappropriateness, and any other harm, is clearly outweighed by other considerations.  In view of the presumption against inappropriate development the guidance explains that the Secretary of State will attach substantial weight to the harm to the Green Belt when considering any planning application or appeal concerning such development.  

14.  Paragraph 3.4 continues that the construction of new buildings inside the Green Belt is inappropriate development unless it is for certain purposes, including the "limited extension, alteration or replacement of existing dwellings (subject to paragraph 3.6 below)". Paragraph 3.6 then provides:

		"Provided that it does not result in disproportionate additions over and above the size of the original building, the extension or alteration of dwellings is not inappropriate in Green Belts.  The replacement of existing dwellings need not be inappropriate, providing the new dwelling is not materially larger than the dwelling it replaces.  Development plans should make clear the approach local planning authorities will take, including the circumstances (if any) under which replacement dwellings are acceptable."

15.  The Local Development Plans relevant in this case are the Surrey Structure Plan and the Guildford Borough Local Plan.  Policy H9 of the Local Plan deals with extensions to a dwelling in the countryside.  Policy H9 is accompanied by an explanatory text which contains guidance in relation to the issue of extensions in the Green Belt.  Paragraph 5.39 reads as follows:

		"It is not considered desirable to state categorically what maximum size of extension outside settlements is permissible given the wide range of circumstances to which the policy applies, other than the general requirement that it should not result in disproportionate additions taking into account the size of the extension itself on the openness of the Green Belt and the visual amenities of the Green Belt in terms of its size, scale, design, materials and character.  Small extensions, even where there have been a number of previous extensions to the original dwelling, will not necessarily be refused.  'Original building' means the dwelling and domestic outbuildings as existing on 1 July 1948; or if no dwelling existed on that date then 'original building' means the dwelling as first built after 1 July 1948, excluding any extensions or outbuildings built after completion of the dwelling."

No percentage increase figures are set out in terms of the application of the policy.

The Decision Letter
16.  In his decision letter the Inspector identified the main issue at paragraph 2.  At paragraph 3 he set out his findings as to the history of the property and its location within a low-density estate.  He found that the majority of the properties were set in spacious plots and that they had been extended since 1948.  In paragraph 4 he identified the property's location within the Green Belt, in an area of outstanding natural beauty and in an area of great landscape value.  He also noted that the property was outside any defined settlement.  At paragraph 5 he set out his findings as to the original dwelling, the extensions which had occurred and the 134 per cent size increase, which the appeal proposal would represent, over the original dwelling.  In paragraph 6 he said this:

		"National guidance in PPG2 (Green Belts) sets out a general presumption against inappropriate development within Green Belts.  Such development should not be approved except in very special circumstances.  Paragraph 3.4 of the guidance states that the construction of new buildings inside a Green Belt is inappropriate unless it is for one of the purposes clearly specified in that paragraph.  The list includes the 'limited extension, alteration or replacement of existing dwellings'.  This exception is further defined in paragraph 3.6 of PPG2, which states: 'Provided that it does not result in disproportionate additions over and above the size of the original building the extension or alteration of dwellings is not inappropriate in Green Belts'."

17.  In paragraphs 7 and 8 of the decision letter the Inspector turned to the relevant provisions of the development plan.  Having concluded that the Surrey Structure Plan reiterated the guidance in PP2 (Green Belts), he dealt with Policies H9 and RE2 of the local plan.  He noted that H9 reiterated a presumption regarding extensions which are disproportionate additions "taking into account the size of the original dwelling".  He quoted the supporting text to policy H9, which says that it is considered undesirable to have a categorical statement as to the maximum size of extension permitted, and which identifies the "principal consideration" as being the potential impact of a proposal against the openness and visual amenities of the Green Belt.  At paragraph 9 the Inspector said this:

		"It is clear from the evidence adduced on behalf of the appellants and from my inspection of the subject property, including its internal layout, that Fallows End is one of the smallest houses on the estate, although it sits within one of the largest domestic curtilages.  I accept that the existing internal layout in terms of both the living and bedroom accommodation is limited and that the proposed extension will provide a more balanced layout appropriate to the spacious plot within which the house is sited.  In terms of the enhanced and extended accommodation I do not consider that the scheme will be disproportionate given that a larger living room and principal bedroom will be created more in keeping with modern expectations, whilst the provision of a small music room and second bedroom (making five bedrooms in all) will not be disproportionate to the existing four bedroom first floor accommodation, which is of somewhat constrained proportions."

18.  In paragraph 10 the Inspector turned to consider the bulk and scale of the extension and its impact upon the host building.  He expressed the view that the overall appearance of the existing structure would be improved as a result of the development proposed. At paragraph 11 he dealt with the visual impact of the extension upon the appearance of the area of outstanding natural beauty from certain viewpoints such as the nearby public footpath.  At paragraph 12 he considered the visibility of the extension.  He found that it would not be objectionable.  At paragraph 13 he concluded that, with appropriate materials, the extension would have no adverse impact on the landscape.  He said:

		"Furthermore, its impact upon the openness of the Green Belt will be minimal and in policy terms, as outlined above, is permitted by virtue of the exceptions set out in the Development Plan and in PPG2."

At paragraph 14 the Inspector dealt with an objection raised by a neighbouring property.  At paragraph 15 he rejected the idea that permitting the extension would permit an adverse precedent.  He noted that Stile Cottage had in the past received permission to extend and "that the majority of houses on the estate have been extended, some by as much as 209 per cent".

Legal Principles
19.  The legal principles applicable in this case are threefold.  The first relates to applications under section 228 of the 1990 Act.  The basal principle is that a decision may only be challenged on administrative law grounds: Seddon Properties Limited v Secretary of State (1978) P&CR 26 at 26-28.  Thus to avoid review a decision must take into account relevant considerations, but ignore irrelevant considerations.  In an oft-cited passage Lord Hoffmann held that the weight to be attached to material considerations and matters of planning judgment are within the exclusive jurisdiction of the decision maker: Tesco Stores Ltd v Secretary of State [1995] 1 WLR 759 at 780F-H.  If an error is identified in a decision, the error must materially affect the decision.

20.  Secondly, there are the well accepted principles for interpreting an Inspector's decision letter.  It must be read in good faith and references to policies must be taken in the context of the whole document.  The adequacy of the reasons must be assessed by reference to whether the decision in question leaves room for genuine doubt as to what the decision-maker has decided and the reasons for it.  In a compendious statement in South Bucks District Council v Porter (No 2) [2004] UKHL 33, [2004] 1 WLR 1953, Lord Brown said:

		"36.  The reasons for a decision must be intelligible and they must be adequate.  They must enable the reader to understand why the matter was decided as it was and what conclusions were reached on the 'principal important controversial issues', disclosing how any issue of law or fact was resolved.  Reasons can be briefly stated, the degree of particularity required depending entirely on the nature of the issues falling for decision.  The reasoning must not give rise to a substantial doubt as to whether the decision-maker erred in law, for example by misunderstanding some relevant policy or some other important matter or by failing to reach a rational decision on relevant grounds.  But such adverse inference will not readily be drawn.  The reasons need refer only to the main issues in the dispute, not to every material consideration.  They should enable disappointed developers to assess their prospects of obtaining some alternative development permission, or, as the case may be, their unsuccessful opponents to understand how the policy or approach underlying the grant of permission may impact upon future such applications.  Decision letters must be read in a straightforward manner, recognising that they are addressed to parties well aware of the issues involved and the arguments advanced.  A reasons challenge will only succeed if the party aggrieved can satisfy the court that he has genuinely been substantially prejudiced by the failure to provide an adequately reasoned decision."

21.  Thirdly, there are the relevant principles governing the application of development policies.  Section 38(6) of the Planning and Compulsory Purchase Act 2004 provides that, if regard is to be had to the development plan for the purpose of any determination, the determination must be made in accordance with the plan unless material considerations indicate otherwise.  Under section 70 of the 1990 Act regard must be had to the provisions of the development plan, along with other material considerations, when determining applications.  The courts have made clear that it is for the decision maker to interpret planning policies.  The court will not interfere with an inspector's interpretation if it is one which a policy can properly bear: The Queen v Derbyshire County Council, ex parte Woods [1997] JPL 958 at 967-968, per Brooke LJ.  However, the decision maker must have interpreted a planning policy properly.  If the decision maker fails properly to understand the policy, the decision is in effect as if no regard had been paid to the policy.

22.  Finally, there are the principles applicable to the planning policy at issue in this case.  The leading decision is R(Heath and Hampstead Society) v Camden London Borough Council [2008] EWCA Civ 193; [2008] 2 P&CR 13.  That case involved an application for a replacement house on metropolitan open land.  The house was on a site adjacent to Hampstead Heath.  The proposed new house would be larger than the existing house, although no higher because much of the increase would be below ground level.  The increased size was calculated in various ways: as a two-and-a-half times increase in footprint; as a threefold increase in floor space; and as a fourfold increase in built volume.  Local planning policy applied paragraph 3.6 of PPG2 (Green Belts) to the replacement of existing dwellings in relation to metropolitan open land.  The local authority granted permission for the new house on the basis that the proposal was consistent with the relevant policies because it would not be materially larger.  

23.  The Court of Appeal held that the local authority had misunderstood and misapplied the relevant policy.  Had it properly understood the policy, it could not reasonably have concluded that the replacement building was not materially larger.  Carnwath LJ, who gave the leading judgment with which Sedley and Waller LJJ agreed, said at paragraph 23 in respect of the decision in Surrey Homes Limited v Secretary of State for the Environment (unreported), that that decision was undoubtedly right but was of little help, since in that case it had been held that a small increase in floor space in absolute terms could be judged material in planning terms because of the design of the building and its position on the site.  Carnwath LJ explained that the converse did not necessarily follow.  The case was no authority for the proposition that design and location could procure the result that a very large increase in absolute terms was to be treated as not material.  

24.  Carnwath LJ then held that "materially larger" in paragraph 3.6 could not be read in isolation.  It was concerned with appropriate development, as contrasted with inappropriate development, which by definition was harmful to the Green Belt.  Thus the first stage of the analysis was concerned principally with categorisation, rather than individual assessment.  Carnwath LJ continued that the test was whether the replacement was materially larger.  Had it been intended to make appropriateness dependent on a broad, no greater impact test, those words could have been used.  Instead, the emphasis was on relative size, not relative visual impact.  That led to the second aspect of the context, which was that of paragraph 3.6 itself.  Carnwath LJ said:

		"36.  .... 'Limited' to my mind implies a limitation of size.  Paragraph 3.6 deals with both extension and replacement.  An extension must be 'proportionate' to the size of 'the original building'.  The emphasis given to the word 'original' shows how tightly this is intended to be drawn, in order presumably to avoid a gradual accretion of extensions, each arguably 'proportionate'.  It would be impossible, in my view, to argue that 'proportionate' in this context is unrelated to relative size.  For example, an extension three times the size of the original, however beautifully and unobtrusively designed, could not, in my view, be regarded as 'proportionate' in the ordinary sense of that word."

In paragraph 37 Carnwath LJ explained that the words "replacement" and "not materially larger" had to be read together and in the same context.  He added:

		"The qualification provides the necessary flexibility to allow planning judgment and common sense to play a part, and it is not a precise formula."

Guildford's Case
25.  In characteristically cogent submissions, Mr Albutt submits that in granting planning permission for the extension of the dwelling in the Green Belt the Inspector failed to have adequate regard to the guidance set out in PPG2 (Green Belts) as to the circumstances in which an extension to an existing dwelling may be considered appropriate development.  In particular he submits that the Inspector failed properly to consider, as required by paragraph 3.6, whether the proposed replacement dwelling would be a limited extension in terms of it being a disproportionate addition over and above the size of the original dwelling.  That test, he says, was not an assessment of the respective impacts on the openness or visual amenity of the Green Belt.  A reading of the decision letter leads to the conclusion that the Inspector wrongly applied the tests in PPG2.  The only reasonable inference could be that the Inspector could not have concluded that the proposed dwelling was proportionate to the original building and would therefore not constitute inappropriate development in the Green Belt.

26.  By reference to Heath and Hampstead Society [2008] EWCA Civ 193; [2008] 2 P&CR 13, Mr Albutt submits that the first stage of the analysis needed to focus on categorisation rather than individual assessment.  The extension, alteration or replacement had to be limited, which meant a limitation of size.  The test was the same in relation to extensions as it was in relation to replacement buildings, the situation which the Court of Appeal faced in Heath and Hampstead Society.  In this case the Inspector compared the existing building with the proposed building and did not carry out a comparison with the original building.  At paragraph 5 he referred to the "proposed extension", which differentiated the appeal scheme from the enhanced and extended accommodation to which he referred in paragraph 9.  He also referred to it as "the scheme", which meant the appeal proposal.  Thus the "enhanced and extended accommodation" meant the existing dwelling with its extension.

27.  In paragraph 9, the Inspector recorded that Fallows End was one of the smallest houses on the estate but sat within one of the largest domestic curtilages.  The Inspector accepted that the existing internal layout was limited and that the proposed extension would provide a more balanced layout.  The Inspector went on to say that in terms of the enhanced and extended accommodation the Inspector did not consider that the scheme would be disproportionate.  The Inspector referred to the provision of a small music room and second bedroom, which would not be disproportionate to the existing four-bedroom first-floor accommodation.  Thus, Mr Albutt contends, in paragraph 9 the Inspector was not comparing the size of the Moffats' proposal with the original building and consequently he erred in law.  

28.  Given that paragraph 3.6 of PPG2 (Green Belts) represents a threshold test of appropriateness, submits Mr Albutt, questions of impact on openness and visual amenity did not arise unless the quantitative increase was marginal.  Consequently, given that the Inspector's conclusion was that the extension represented an increase of 134 per cent (an increase of two-and-one-third times), there was no rational basis for concluding that the resulting extension was "a limited extension" and proportionate over and above the size of the original building.  The Inspector gave consideration to the enhanced and extended accommodation, which was the existing dwelling with its two extensions, and compared that with the appeal scheme.  His comparison of the proposed five-bedroom property to the existing four-bedroom first-floor accommodation was not a test of comparing the appeal proposal with the size of the original building and thus he did not address whether it was disproportionate.  This error went to the heart of his decision letter.  The result of his finding that the development was appropriate in the Green Belt meant that he did not consider the appeal proposal to be inappropriate development in the Green Belt and did not then go on to consider any very special circumstances to justify the appeal scheme.  The Inspector's comparison with what Guildford had permitted elsewhere on the estate was a matter which the Inspector should have treated with the greatest of caution.  

Discussion
29.  In my view the Inspector's letter must be interpreted firstly, against the backdrop of the way Guildford advanced its case, and against the local policy H9 and its phraseology.  It will be recalled that Guildford's case was not confined to the issue of whether the extension was disproportionate to the original dwelling.  In addition to that aspect, Guildford also advanced arguments that the extension would have an unacceptable impact on the scale and character of the existing building.  Consistent with the reasons for its refusal of planning permission, it was clear that the Inspector was required to address not only the issue of the size increase from the original dwelling, but also whether the proposed development would, by virtue of its size, design, bulk and width have an unacceptable impact on the existing building. 

30.  Under section 38(6) of the 2004 Act the Inspector had to consider the proposal against local policy H9, including the direction as to the "principal consideration" (as the commentary to H9 puts it), which requires an assessment of the proposal in terms of its impact on visual amenities and its size, scale, design, materials and character generally.  Thus, on the particular issue of the Green Belt and the test under local policy H9 the Inspector had to address the scale of the proposed extension not just against the original building, but also against the existing building.  That explains in part the way the decision letter is couched.

31.  Secondly, the decision letter has to be interpreted in line with the authorities, which were synthesized by Lord Brown in the passage I have quoted from South Bucks District Council v Porter (No 2) [2004] UKHL 33; [2004] 1 WLR 1953 (paragraph 36).  In paragraph 5 the Inspector recorded the existence of extensions to the original dwelling.  He then identified the original floor area of the dwelling (149.4 square metres), the existing floor area (235.8 square metres), and the size of the proposed extension (114.1 square metres).  Significantly, he explained that the appeal scheme represented an overall increase upon the original dwelling of 134 per cent, including the extensions previously erected.  He did not make a comparison with the existing building and the percentage increase, namely 48 per cent. In paragraph 6 he set out in terms the relevant advice contained in PPG2 (Green Belts) and he concluded that the development was permitted by virtue of the exception contained in it in paragraph 13 of his decision letter.

32.  Paragraph 9 of the decision letter, as Mr Albutt's critique has aptly demonstrated, is unfortunate.  However, the authorities make clear that it would be wrong for me to take that paragraph out of context and to subject it to forensic examination without reference to the whole of the decision letter.  The other paragraphs, in my judgment, reveal that, in addition to properly directing himself as to PPG2 (Green Belts), the Inspector also properly directed himself as to the application of the relevant policies, in particular local policy H9 and paragraph 5.39 in the explanatory text.

33.  For Guildford to succeed, I would have to conclude that, having set out the test in paragraph 3.6 of PPG2 (Green Belts), the Inspector failed to apply it.  I would need to rationalise the terms of paragraph 5, where the Inspector specifically analysed the sizes of the extensions which had occurred, and then carried out a percentage analysis of the overall size increase of the proposal over the original building, without mention of its size increase over the existing building.  (I note in passing as well that those parts of his reasons in which he accepted evidence about the size increases which had been permitted on the estate were calculated in terms of the original dwelling.)  I would have to ignore paragraph 13, where the Inspector specifically identified that he considered that the PPG2 (Green Belts) test had been satisfied.  I would also have to distort the overall reasoning in the decision letter by an undue concentration on paragraph 9 and by ignoring the issues which Guildford itself had asked the Inspector to consider, such as an assessment of the extension's effect, as compared with the existing building.  None of this I am prepared to do.

34.  Nothing in Heath and Hampstead Society [2008] EWCA Civ 193; [2008] P&CR 13 affects my conclusion.  The ratio of that case was that the first stage of the analysis in relation to paragraph 3.6 of PPG2 (Green Belts) is concerned primarily with categorisation rather than individual assessment.  The second aspect of the context is, as the court held, paragraph 3.6 itself.  The test for categorisation was, the court held, size.  "Limited" implied a limitation of size, and size was the primary test.  There is the obiter dictum of Carnwath LJ at paragraph 36 of the judgment that an extension three times the size, "however beautifully and unobtrusively designed", could not in his view be regarded as proportionate in the ordinary sense of the word.  In that case the increase was three times floor space, but a two-and-a-half times increase in terms of footprint, and a four times increase in terms of overall volume.  At paragraph 37 of his judgment, Carnwath LJ continued that the qualification (ie proportionality) "provides the necessary flexibility to allow planning judgment and common sense to play a part".  Thus the court was re-asserting that there is a judgment to be exercised as to proportionality in the light of the nature of the dwelling and its location.  The categorisation issue is referable to issue of size, but that may include size in relation to footprint, floor space or volume.  

35.  Moreover, it seems to me that, in the exercise of planning judgment a relevant consideration may be the local authority's own approach to similar applications in the locality.  Public law principles demand consistency in the application of policies by public bodies such as local planning authorities, unless there are good reasons to the contrary.  Consistency is required as a broad principle of good administration and derives from general principles of fairness in the treatment of citizens.

36.  In this case the evidence was that in previous years Guildford had granted permission for substantial increases over the original size of dwellings on the estate.  None of those permissions was appealed.  All but one preceded the decision at first instance in Heath and Hampstead.  It seems to me that the Inspector was entitled to regard the previous decisions on extensions in the immediate area of the Moffats' property as a relevant consideration in deciding this appeal.

Conclusion
37.  In my judgment Guildford's challenge cannot succeed.  The Inspector properly directed himself.  He applied PPG2 (Green Belts) and the local policy.  For the purpose of those policies he considered the increase to the size of the original building which the proposal represented.  He also addressed his mind to the other issues which had been raised in the appeal before him.  He reached a clear conclusion that the policy tests in PPG2 (Green Belts) and H9 were satisfied.  That does not mean that one cannot have sympathy for Guildford in their challenge.  Another Inspector, in his or her planning judgment, might well have concluded that a 134 per cent increase over the size of the original dwelling was a disproportionate extension.  Guildford are also hampered by their own previous decisions where substantial percentage size increases had been accepted as proportionate in the immediate vicinity of the Moffats' dwelling.  That was a relevant consideration to which the Inspector could give attention, and he did.  However, for the reasons I have given there is no error in the Inspector's decision and I refuse the application.

MR STRACHAN:  My Lord, I would ask for an order in those terms and also an order that the claimant pay the defendant's costs.  I am pleased to say that I think that there is an agreed sum of £6,379.

MR JUSTICE CRANSTON:  Good.

MR ALBUTT:  My Lord, I cannot argue with that.

MR JUSTICE CRANSTON:  I will award order costs in that amount. 

MR ALBUTT:  My Lord, this is obviously a decision which is of considerable importance to Guildford in terms of the interpretation of its policy and, as you are aware, on behalf of Guildford I would make an application for permission to appeal, particularly in the light of the importance of the interpretation of that policy, in particular Policy H9.

MR JUSTICE CRANSTON:  I think, Mr Albutt, you will need to go elsewhere on this occasion.  Can I thank the two of you for the excellent way that you prepared the case?  It made it so much easier to consider the issues and to give judgment.  Thank you very much.