Appeal 3334959

Appeal A is allowed and planning permission is granted for ‘side extension of existing garage at ground level, with basement level garage including turntable and games/leisure room’ at [site address] in accordance with the terms of the application, Ref 23/00950/FULL1, subject to the conditions in the attached Schedule 1.

Appeal B is allowed and planning permission is granted for ‘extension of the existing garage at ground level, with basement level garage and games/leisure room’ at [site address] in accordance with the terms of the application, Ref 24/00109/FULL1, subject to the conditions in the attached Schedule 2.

As set out in the banner headings above, there are two appeals on this site, each proposing an extension with basement. I have considered each appeal on its individual merits. However, to avoid duplication I have dealt with the two schemes together, except where otherwise indicated.

The description of the Appeal A development in the banner heading and my formal decision above is taken from the appeal form. This differs slightly from the description entered on the application form but is consistent with the Council’s decision notice and I consider it to more accurately describe the Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744 development shown on the submitted plans. As a result and because it is used by both main parties, I am satisfied that no injustice would be caused by my use of this description.

The main issue in each appeal is whether or not the proposal would comprise inappropriate development in the Green Belt.

The National Planning Policy Framework (‘the Framework’) advises that the construction of new buildings is inappropriate in the Green Belt, although some exceptions to this principle are specified. These include the extension of a building provided that it does not result in disproportionate additions over and above the size of the original building1. Policy 49 of the Bromley Local Plan 2019 (‘the LP’) includes a similar provision. However, neither the Framework nor LP Policy 49 define ‘disproportionate additions’.

Policy 51 of the LP does set out that extensions or alterations to dwellinghouses in the Green Belt will only be permitted if, amongst other things, the net increase in the floor area over that of the original dwellinghouse2 is no more than 10% as ascertained by external measurement. The supporting text to the policy indicates that the Council wishes to ensure that there is no incremental harm to the Green Belt by excessive subsequent extensions that collectively may jeopardise the open nature of the countryside or other open land. Be that as it may, I have not been directed to any statement that the allowance for a 10% net increase in floor area in the policy defines a threshold of what would constitute ‘disproportionate additions’ in the terms of the Framework and LP Policy 49. Instead, I consider it important to take an overall view of the additions relative to the original building in considering this matter.

Both main parties suggest that the Appeal A proposal would result in a 30.6% increase in floor area over that of the original building. This would exceed the 10% increase referenced in Policy 51 of the LP. However, the original dwellinghouse is a substantial mansion, including double-height spaces to the ground-floor level of the historic core. As the Council notes, it is therefore much larger in volumetric terms than the floor area would suggest. Appreciated against this context, the increase in floor area would in my judgment be seemingly modest and far from disproportionate. Moreover, the basement level would add to the floor area, but would have no external visible presence on the site. The visible part of the extension would be deeper than some parts of the building and only slightly lesser depth than the adjacent wing, but it would be of limited relative width. It would also be single-storey, with a flat roof set below the first-floor windows to the adjacent part of the building, and its height would be very limited in comparison to the historic core.

Overall, I find that the additions proposed in Appeal A would be modest in relative scale and that the bulk and mass of the development would be understated and unobtrusive against the building. In my assessment, it would not result in disproportionate additions over and above the size of the original building and the proposal would accordingly comprise an exception to inappropriate development under the terms of the Framework and LP Policy 49. 1 Defined as ‘a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was built originally. 2 Defined in the LP as following the definition of ‘original building’ in the Framework. Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744

Both main parties indicate that the Appeal B proposal would result in around a 25% increase in floor area over that of the original building. This would exceed the 10% increase referenced in Policy 51 of the LP, but to a lesser degree than in Appeal A where I have already found that the increase in floor area would not be disproportionate. Moreover, the Appeal B scheme would be of comparable scale and design to the Appeal A scheme at ground-floor level and while the basement would be reduced, it would still accommodate over half of the additional floor area proposed with no external visible presence on the site. Having regard to the similarity between the proposals and noting the smaller increase in floor area, I find for the same reasons as Appeal A that that the Appeal B scheme would not amount to disproportionate additions over and above the size of the original building. It would also therefore comprise an exception to inappropriate development under the terms of the Framework and LP Policy 49.

The Council’s case in relation to both appeals refers to built form extending into the open setting of the building and suggests a spatial impact on openness of the Green Belt and conflict with the Green Belt aim of preventing urban sprawl. However, as an exception to inappropriate development within the Green Belt, the proposals should not be regarded as harmful to the openness or purposes of Green Belt.

Furthermore, with regard to the modest height and scale relative to the host building and the spacing retained within the extensive grounds around it, I find in each case that the development would be a markedly subservient addition. Based on my observations at my visit and the evidence before me, I am satisfied that neither proposal would detract from the visual amenities or the open and rural character of the locality. Nor would either proposal cause detrimental change to the overall form, bulk or character of the original dwellinghouse. While the proposals would each result in increases of more than 10% in floor area over that of the original dwellinghouse, they would therefore comply with other criteria specified in LP Policy 51.

Drawing these matters together, I conclude that while Appeal A and Appeal B would each be contrary to one aspect of LP Policy 51, they would not result in inappropriate development within the Green Belt. The proposals would comply with the Framework and Policy 49 of the LP, as well as with Policy G2 of the London Plan 2021 insofar as it sets out that the Green Belt should be protected from inappropriate development. I further consider having regard to the particular circumstances of the appeal building that the increases in floor area would not be detrimental to the Green Belt or the open nature of the countryside and that this is a material consideration which would outweigh the conflict with LP Policy 51 in these cases.

The appeal building is a [name] listed building, listed as ‘[name]. It is therefore recognised at the highest level of national significance, and I have had special regard to the desirability of preserving the building, its setting or any features of special architectural or historic interest which it possesses in accordance with section 66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (‘the Act’). Although not subject to statutory protection, the building is also part of a Grade II Registered Park and Garden ‘Holwood Park’ (‘the RPG’). Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744

The listed building dates to 1825, although it replaces an earlier building on the site, and is a 15-bay villa designed by the eminent architect [name] in the [name] style. The historic building has a symmetrical form, comprising seven central bays of two-storey height set between lower wings which are flanked by pedimented pavilions. A later wing including a modern swimming pool and garage extends to the north-east side of the building resulting in some unbalancing of its proportions, but it is distinguished from the historic core including through its much lower height which helps to moderate the effect somewhat.

The building occupies an elevated position on [address] and is set within a designed landscape including pleasure grounds to the south of the building with panoramic views across parkland to countryside beyond, a kitchen garden to the north, and extensive areas of woodland and parkland with planting and open pasture which extend out towards the wider countryside. The landscape of the RPG was subject to improvements by [name] under the commission of [name] the Younger while he owned the previous building on the site, and has evolved over time through modifications made by subsequent owners, including tree planting across some historically open areas, as well as some modern development.

Given the above, I consider the special interest and significance of the listed building, insofar as it relates to these appeals, to be primarily associated with its historic and architectural interest as a commanding country house. Despite some later interventions, the carefully balanced proportions and fine detailing of Burton’s accomplished design remain clearly legible and provide for an exceedingly elegant building of considerable architectural quality.

The focal position of the building within spacious grounds and parkland taking advantage of sweeping countryside views allow an appreciation of the building, and provide an attractive rural setting which complements the building and reflects its historic status and grandeur. In this way, I consider the setting of the building to make an important contribution to its special interest and significance. The RPG also has significance in its own right. Insofar as it relates to these appeals, I consider this significance to be primarily associated with the underlying layout and the aesthetic and illustrative value of the designed landscape extending out around the building towards the wider countryside.

In both appeals, the extension would adjoin modern additions to the north-east of the building. It would be of traditional design in keeping with the adjacent part of the building, and reflecting the design of a similar, albeit smaller, garage extension which has extant permission3 (‘the [name]). While there would be a further increase in the width of the building, the extension would be much lower than the adjacent two-storey part of the building which is itself appreciably set down relative to the historic core, and it would also be set back from the adjoining part of the building. In my assessment, it would therefore be a clearly subservient and discreet addition and I am satisfied that the existing unbalancing of the building would not be meaningfully exacerbated. Subject to further details of the materials which could be secured by planning conditions, I concur with Historic England’s comments on the Appeal B proposal that the extension would be deferential to the host building and closely matched such that it would appear part of the 3 Application ref 23/04011/FULL1 Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744 seamless whole. Given that the visible parts of the developments are comparable, this would apply equally to Appeal A.

Furthermore, the development in each case would largely occupy an area of existing hardstanding and while there would be some incursion into the surrounding grounds, this would be very slight. The development would be clearly appreciated as sitting in the immediate environs of the building rather than extending notably into the pleasure grounds or parkland and would not in my judgement detract from the quality or composition of the designed landscape which is also part of the setting to the building.

Overall, I am therefore satisfied that each proposal would preserve the special interest of the [name] listed building and that there would be no harm to the significance of the listed building or RPG, satisfying the requirements of the Act and the Framework.

I have also noted that part of the appeal site falls within the boundary of a Scheduled Monument ‘[name] (‘the SM’). This contains an example of an [name] large multivallate hillfort known as [name]. The list entry notes that large multivallate hillforts are rare, with only around 50 examples recorded nationally. It indicates that the [name] hillfort was built in about 200BC. Ramparts and ditches remain to the north and west, but have been largely levelled by 18th and 19th century landscaping associated with [site address] to the south. Nevertheless, insofar as it relates to these appeals, I consider the surviving earthworks and below-ground remains to have both evidential and illustrative value in informing an understanding of the hillfort design and the people who built and used it, contributing to the significance of the SM.

In both appeals, there would be no encroachment into the defined area of the SM by the extension, including at basement level. However, there would be an extension to the existing driveway, part of which would run through the protected area. That said, I note that the part of the driveway within the SM boundary would be of very limited extent and would avoid direct impacts on the surviving earthworks. The appellant further advises that minimal excavation is envisaged to provide the access, minimising potential for disturbance of any archaeological remains, and further details of the construction could be secured by condition. Moreover, the part of the driveway within the SM boundary would very closely follow that shown as part of the [name] such that direct effects on the SM would be little different. Having regard to the scale and nature of the development proposed outside of the boundary of the SM and its close association with the existing building which is already part of the setting, I am also satisfied that there would not be harm to the significance of the SM through development within its setting.

Works of alteration within the area of the SM would require a separate Scheduled Monument Consent under the provisions of the [name] and Archaeological Areas Act 1979. In the context of these appeals however, I find given the above that there would not be harm to the significance of the SM that would justify dismissing either appeal.

I have noted representations requesting that the private access to the site from [address] is used during construction works rather than the shared access from [site address] which also serves other properties on the [name]. I note that traffic associated with construction works would have some Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744 potential to generate noise or disruption. However, this would be short term, and I have no firm reason to find that they could not be mitigated by careful construction management secured by an appropriately worded condition.

I have considered suggested conditions against the tests set out in the Framework. I have made amendments where necessary to ensure compliance with these tests or for clarity, brevity or consistency.

In addition to standard time limit conditions (1), I have in each appeal imposed a condition specifying the approved plans (2) for the avoidance of doubt and in the interest of certainty.

Conditions requiring details and implementation of archaeological investigation (3), details of construction methods and management (4), details of materials (5) and provision for landscaping (6) are necessary in each case to ensure a satisfactory appearance and in the interests of safeguarding heritage assets, including archaeological interest. I have broadened the requirements of condition 4 from the Council’s suggested condition to include details of how the access will be constructed which I consider is necessary to safeguard the SM. Given that the shared access to the site from [site address] is relatively narrow and that the basements would require excavation which could generate significant levels of construction movements, I have also included a requirement for details of how works will be managed more broadly which I consider is necessary in the interests of the living conditions of nearby occupiers. I have also amended conditions 5 and 6 to require that details are approved before any above ground works as it is unclear from the submitted justification why details of materials or proposed landscaping would be necessary before any development takes place.

In each appeal, conditions 3 and 4 require matters to be approved before development commences as the agreed measures would need to be in place before and during construction. The appellant has provided written agreement to these pre-commencement conditions.

I have noted representations by Historic England seeking a site-wide Conservation Management Plan. However, having regard to the scale and nature of the specific appeal proposals, I consider a planning condition to require this would be unreasonable, and I agree with the Council that such a condition would not meet the test of necessity. I have not therefore imposed it.

I have found that Appeal A and Appeal B would not result in inappropriate development within the Green Belt and that while they would each be contrary to one aspect of LP Policy 51, material considerations would outweigh the conflict.

I therefore conclude that Appeal A and Appeal B should each be allowed.

The development hereby permitted shall begin not later than 3 years from the date of this decision.

Unless otherwise amended under the conditions below, the development hereby permitted shall be carried out in accordance with the following approved plans: 22_139_PL01, 22_139_PL02, 22_139_PL03, 22_139_PL04, 22_139_PL05, 22_139_PL06 and 22_139_PL07.

No development (including demolition) shall take place until an archaeological [name] of Investigation (WSI) has been submitted to and approved in writing by the Local Planning Authority. For land that is included within the WSI, no demolition or development shall take place other than in accordance with the agreed WSI which shall include a statement of significance and research objectives and: A. the programme and methodology of site investigation and recording and the nomination of a competent person(s) or organisation to undertake the agreed works; B. where appropriate, details of a programme for delivering related positive public benefits; and C. the programme for post-investigation assessment and subsequent analysis, publication and dissemination and deposition of resulting material. This part of the condition shall not be discharged until these elements have been fulfilled in accordance with the programme set out in the WSI.

No development (including demolition and all preparatory work) shall take place until a [name] has been submitted to and approved in writing by the local planning authority. The Statement shall include details of: i) a programme of works, including details of how vehicles will access the site from the highway network; ii) details of the construction method(s) and specification to be used for the access proposed between the existing driveway and the extension hereby permitted; and iii) exclusion zones for construction and construction activities, together with a method statement for the protection of the Scheduled Monument from construction activity including vehicular traffic if vehicles are required to pass over the Monument. The development shall be carried out in accordance with the approved [name] throughout the construction period.

No development above proposed ground level shall take place until details and samples of the materials to be used for the external surfaces of the development hereby permitted which shall include roof cladding, wall facing materials and cladding, window glass, door and window frames, decorative features, rainwater goods and paving where appropriate have been submitted to and approved in writing by the Local Planning Authority. The development shall be carried out in accordance with the approved details. Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744

No development above proposed ground level shall take place until details of landscaping and treatment of all parts of the site surrounding the development hereby permitted including the extended access road have been submitted to and approved in writing by the Local Planning Authority. The landscaping works shall be carried out in accordance with the approved details in the first planting and seeding season following the completion of the development. Any new trees that die, are removed or become severely damaged or diseased shall be replaced and any new planting (other than trees) which dies, is removed, becomes severely damaged or diseased within five years of planting shall be replaced with others of similar size and species. End of Schedule SCHEDULE 2 APPEAL B CONDITIONS

The development hereby permitted shall begin not later than 3 years from the date of this decision.

Unless otherwise amended under the conditions below, the development hereby permitted shall be carried out in accordance with the following approved plans: 22_139_PL01, 22_139_PL02B, 22_139_PL04, 22_139_PL05A and 22_139_PL06.

No development (including demolition) shall take place until an archaeological [name] of Investigation (WSI) has been submitted to and approved in writing by the Local Planning Authority. For land that is included within the WSI, no demolition or development shall take place other than in accordance with the agreed WSI which shall include a statement of significance and research objectives and: A. the programme and methodology of site investigation and recording and the nomination of a competent person(s) or organisation to undertake the agreed works; B. where appropriate, details of a programme for delivering related positive public benefits; and C. the programme for post-investigation assessment and subsequent analysis, publication and dissemination and deposition of resulting material. This part of the condition shall not be discharged until these elements have been fulfilled in accordance with the programme set out in the WSI.

No development (including demolition and all preparatory work) shall take place until a [name] has been submitted to and approved in writing by the local planning authority. The Statement shall include details of: i) a programme of works, including details of how vehicles will access the site from the highway network; ii) details of the construction method(s) and specification to be used for the access proposed between the existing driveway and the extension hereby permitted; and Appeal Decisions APP/G5180/D/23/3334959 & APP/G5180/D/24/3350744 iii) exclusion zones for construction and construction activities, together with a method statement for the protection of the Scheduled Monument from construction activity including vehicular traffic if vehicles are required to pass over the Monument. The development shall be carried out in accordance with the approved [name] throughout the construction period.

No development above proposed ground level shall take place until details and samples of the materials to be used for the external surfaces of the development hereby permitted which shall include roof cladding, wall facing materials and cladding, window glass, door and window frames, decorative features, rainwater goods and paving where appropriate have been submitted to and approved in writing by the Local Planning Authority. The development shall be carried out in accordance with the approved details.

No development above proposed ground level shall take place until details of landscaping and treatment of all parts of the site surrounding the development hereby permitted including the extended access road have been submitted to and approved in writing by the Local Planning Authority. The landscaping works shall be carried out in accordance with the approved details in the first planting and seeding season following the completion of the development. Any new trees that die, are removed or become severely damaged or diseased shall be replaced and any new planting (other than trees) which dies, is removed, becomes severely damaged or diseased within five years of planting shall be replaced with others of similar size and species. End of Schedule