Elevational alterations and enlargement of lower ground floor and construction of two storey front extension, two storey side extension (incorporating raised terrace at rear with lower ground and ground floor space) with single storey side/rear extension and alterations to roof profile/design, with front, side and rear dormers and conversion of roof space to habitable accommodation. Enlargement of existing rear terrace

Appeal Decision Site visit made on 26 November 2025 by R Cahalane BA(Hons) MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 17 December 2025 Appeal Ref: 6000453 Warbank House, Westerham Road, Keston, Bromley BR2 6AG • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Mr Raj Singh against the decision of the Council of the London Borough of Bromley. • The application Ref is DC/25/01052/FULL6. • The development proposed is elevational alterations and enlargement of lower ground floor and construction of two storey front extension, two storey side extension (incorporating raised terrace at rear with lower ground and ground floor space) with single storey side/rear extension and alterations to roof profile/design, with front, side and rear dormers and conversion of roof space to habitable accommodation. Enlargement of existing rear terrace. Decision 1. The appeal is dismissed. Preliminary Matter 2. I have taken the description of development within the banner heading above from the decision notice, rather than the application form. The decision notice description provides more detail and accurately describes the proposal. Main Issues 3. The main issues are: • whether the proposed development is inappropriate development in the Green Belt having regard to the National Planning Policy Framework (the Framework) and relevant development plan policies, including the effect on the openness and purposes of the Green Belt; • the effect on the character and appearance of the host dwelling and the surrounding area; and • whether any harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations so as to amount to very special circumstances required to justify the appeal scheme. Reasons Inappropriate development 4. The appeal site is within the Green Belt as designated on the Policies Map of the Council’s Local Plan (LP) (adopted 2019). Policy 49 of the LP is consistent with the Framework insofar as it sets out that apart from a number of exceptions, the construction of new buildings in the Green Belt is inappropriate. Permission will not Appeal Decision 6000453 2 be given for inappropriate development unless very special circumstances can be demonstrated that clearly outweigh the harm by reason of inappropriateness or any other harm. One such exception is the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original building. 5. Policy 51 of the LP provides further detail in respect of extensions or alterations to dwellinghouses in the Green Belt. Such development will only be permitted if, among other things, the net increase in the floor area over that of the original dwellinghouse is no more than 10%, as ascertained by external measurement. The glossary to the LP does not provide a definition of what constitutes an “original dwellinghouse”. The Framework however defines this as “a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was built originally.” 6. The officer report advises that the existing floorspace of the dwelling at lower ground floor level is approx. 320 sqm, and approx. 238sqm at first floor level. The additional floorspace proposed would, at lower ground floor level, be approx. 240sqm. At ground floor, the additional floorspace would be approx. 102sqm, and the additional floorspace at first floor level would be 141sqm. 7. The overall additional floorspace, including the accommodation in the roofspace, would therefore be approx. 483sqm, or approx. 342sqm when excluding the roofspace. This amounts to a percentage increase of approx. 86% including the roofspace accommodation, or 61% when excluding the roofspace. The appellant has not disputed the above figures. The submitted evidence does not clarify whether the above existing figures represent the floor area of the original dwellinghouse. Therefore, for the purposes of this appeal I have taken these figures as amounting to the original dwellinghouse. 8. The Framework states that openness is an essential characteristic of the Green Belt. The Supreme Court1 has held that a consideration of openness in any given case is a matter for the decision maker and may or may not include a consideration of the visual aspect of openness. For the purposes of this appeal, I have considered both the visual and spatial aspects of openness. 9. Much of the proposal would be sited above the existing footprint. I also accept that new development does not automatically mean that it will be inappropriate in the Green Belt, or compromise openness. 10. The appeal scheme would nonetheless in spatial terms lead to a substantial spread of development beyond the existing built form. The side extension to provide the gym and office space would appear as a new building when viewed from the front, due to the partially subterranean section linking to the existing dwelling. The overall proposed additions would also substantially increase the size of both side profiles of the dwelling. Its rear profile would also be significantly wider on account of the additional two storey built form to the side. 11. Taken together, these additions would amount to a substantial size increase to the property. I find these increases to be disproportionate over and above the size of the original dwellinghouse, contrary to Policies 49 and 51 of the LP. Comparison to the large size of the appeal site, other nearby larger dwellings on large plots, and 1 R (on the application of Samuel Smith Old Brewery (Tadcaster) and others) (Respondents) v North Yorkshire County Council (Appellant) [2020] UKSC 3 Appeal Decision 6000453 3 the long distances from the extensions to the site boundaries, are not factors that can alter this conclusion. 12. The appeal site and dwelling are well obscured from the road by landscaping, and ground levels decline significantly to the rear. Whilst the visual impact on the openness of the Green Belt may therefore be limited, the additions to the dwelling would nonetheless reduce the openness of the Green Belt in spatial terms. 13. In overall spatial and visual terms, the proposal would have a greater impact on the openness of the Green Belt than the existing situation. Whilst the overall harm in this regard would be moderate, this would be contrary to the Framework where it states that an essential characteristic of Green Belts is their openness. 14. I therefore conclude that the proposal is inappropriate development in the Green Belt having regard to the Framework and Policies 49 and 51 of the LP. In this respect, the scheme also conflicts with Policy G2 of the London Plan which states that the Green Belt should be protected from inappropriate development. Character and appearance 15. The proposed side extensions would add considerable width to the host dwelling. I also accept that the gabled forms and external detailing of the side extensions noticeably differ from the host dwelling and that from many locations within the site, the extension providing the gym and office space would appear as a new building. 16. However, Warbank House does not appear as a historic dwelling, nor does it have any particular architectural merit. Given this along with the large site size that is well screened from the road, contemporary and sizeable built forms and layouts such as the appeal scheme can be accommodated without causing harm to the character and appearance of Warbank House and the surrounding area. 17. The proposed dormers would be numerous, which would draw the eye upwards. They would however be of traditional pitched roof form and modest size relative to the existing dwelling, and well set in from the existing main ridge, side hipped roof lines and eaves level below. This follows the specific requirements of Policy 6 of the LP, as it states that dormer windows should be of a size and design appropriate to the roofscape and sited away from prominent roof pitches. 18. Overall, I conclude that the proposal would not harm the character and appearance of Warbank House and the surrounding area. In this respect, the proposal would comply with Policies 6 and 37 of the LP, and Policy D3 of the London Plan. These policies require, amongst other things, building extensions to be of a high quality, standard of design and layout, and respect space or gaps between buildings. Other considerations 19. Warbank House does not hold any particular architectural merit and the proposal would give the dwelling an additional presence and stature. That is not to say however that the existing dwelling appears unattractive in its context. The design merits of the appeal scheme are therefore only afforded limited weight. 20. The development would provide a modern family home and leisure facilities for an active family. It is not however been demonstrated that the appeal scheme is the only or least harmful way in Green Belt terms to cater for the appellant’s needs in these respects. I therefore ascribe limited weight in favour of these benefits. Appeal Decision 6000453 4 21. I have found that the appeal proposal would not harm the character and appearance of the host dwelling, which is also not within a conservation area or an area at known risk of flooding. The lack of harms in these respects neither weigh in favour nor against allowing this appeal. Other Matters 22. Reference is made to recent appeals that allowed over 200 homes in the Green Belt at Chapel Road, Tandridge, and up to 30 homes allowed in the Green Belt in Buckinghamshire. The full details of these schemes are not before me. In any event, they relate to different development types than as proposed under this appeal. They would have also turned on their own site-specific merits. Those appeal decisions are therefore not useful comparisons to the current scheme before me, and do not justify allowing this appeal. Green Belt Balance 23. For the above reasons, the proposal is inappropriate development in the Green Belt that is, by definition, harmful to the Green Belt. Whilst the impact on the Green Belt in visual terms would be limited, this effect would still harm the openness of the Green Belt and therefore cannot amount to very special circumstances. The Framework requires substantial weight to be attached to any harm to the Green Belt. There is sufficient conflict with Policies 49 and 51 of the LP arising from this harm that amounts to conflict with the development plan as a whole. 24. Policies 49 and 51, along with the Framework, set out that very special circumstances will not exist unless the potential harm to the Green Belt by reason of inappropriateness, and any other harm, is clearly outweighed by other considerations. Collectively, the other considerations in this case do not clearly outweigh the harm that I have identified. Consequently, the very special circumstances necessary to justify the development in Green Belt policy terms do not exist. Nor are the other considerations material so as to justify a decision other than in accordance with the development plan. Conclusion 25. The proposal conflicts with the development plan and the material considerations do not indicate that the appeal should be decided other than in accordance with it. The appeal is therefore dismissed. R Cahalane INSPECTOR