To demolish existing conservatory and erect a single storey side extension

Appeal Decision Site visit made on 23 June 2026 by Lynne Evans BA MA MRTPI MRICS an Inspector appointed by the Secretary of State Decision date: 28 July 2026 Appeal Ref: 6010140 Amberwood Cottage, St Catherines Hill Lane, Christchurch Dorset BH23 2NL • 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 Ms Tanya Wiltshire against the decision of BCP Council. • The application Ref is P/26/00392/HOU. • The development proposed is to demolish existing conservatory and erect a single storey side extension. Decision 1. The appeal is dismissed. Main Issues 2. The main issues in this appeal are: • Whether the proposal would be inappropriate development in the Green Belt having regard to the National Planning Policy Framework and relevant development plan policies; and the effect of the proposal on the openness of the Green Belt; • Whether the harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations, so as to amount to the very special circumstances required to justify the proposal. Reasons Whether inappropriate development and the effect on openness 3. The appeal property is a detached, single storey cobb cottage on a generous plot which has previously been extended and altered with a number of annexes and outbuildings within the garden area. The surrounding area of St Catherine’s Hill includes individual dwellings on generous plots in a wooded setting towards the northern edge of Christchurch. The property is locally listed and forms a group with two other similar properties, one of which is statutorily listed. The site lies within the Southeast Dorset Green Belt. 4. The proposal seeks to replace an existing conservatory with a single storey side extension. The proposed extension would be built with brick walls under a pitched slate roof. On the basis of the Council’s figures, it would be wider and deeper than the existing conservatory with a footprint of some 31 sqm compared with the 17 Appeal Decision 6010140 2 sqm for the existing conservatory, and higher, having a ridge height of some 5 m compared with the height of the existing conservatory at 3.3 m. 5. Paragraph 154 of the National Planning Policy Framework (Framework) sets out that the construction of new buildings in the Green Belt is inappropriate except for a limited number of exceptions including c) the extension or alteration of a building providing that it does not result in disproportionate additions over and above the size of the original building. The Glossary at Annex 2 of the Framework defines an original building as a building as it existed on 1 July 1948, or if constructed after 1 July 1948, as it was built originally. The term ‘disproportionate’ is not further defined. 6. The Council’s decision notice also refers to Policy KS3 of the Christchurch and East Dorset Core Strategy Part 1 (2014) (Core Strategy) and Policy H14 of the Christchurch Local Plan (2001) (Local Plan). Policy H14 of the Local Plan is a criteria based policy in respect of extensions to dwellings in the Green Belt and sets out that extensions to existing dwellings will only be granted planning permission if the proposed extension does not significantly increase the size of the existing dwelling; the scale, design and materials of the proposal is in keeping with the character of the dwelling and its surroundings and the proposed extension would not facilitate the creation of a separate dwelling. The term ‘significantly increase’ does not appear to be defined. Policy KS3 of the Core Strategy indicates that development will be contained by the Southeast Dorset Green Belt and sets out criteria for development on previously developed sites. Whilst I have regard to both of these policies, the weight I can attach is reduced given that they do not fully accord with the relevant provisions of the Framework. 7. The Council has set out its understanding of the floorspace figures arising from the various extensions and additions undertaken. The Appellant has not provided any alternative figures and has not sought to dispute the Council’s figures. The original cobb cottage is believed to date from the 18/19th century and was likely to be of very modest proportions. The original cottage appears to have been significantly extended, especially to the north and west although the Council has advised that the dates of some of these extensions are not known, but has calculated the footprint of the original building (as of 1 July 1948) to be around 44 sq m. When account is taken of the existing conservatory and the two authorised house extensions as well as the two authorised annexes there has been the addition of around 162 sqm to the original building footprint, and this would increase to about 176 sqm when the floorspace from the proposed extension, less the existing conservatory is added. This equates to approximately a 400% increase on the original floorspace. 8. Even if the calculations were confined to the existing extensions to the cobb cottage together with the proposal before me (less the existing conservatory), there would still appear to be an increase in excess of 100% over the floorspace of the original building, as calculated by the Council. 9. Given the size of the original building and the subsequent alterations and extensions already permitted and built out, the proposal would contribute towards a very substantial increase in floorspace over the original dwelling. Taking all these matters into account the proposal would be a disproportionate addition to the original building in relation to the exception set out under paragraph 154 c) of the Framework. Appeal Decision 6010140 3 10. Compared with the existing lightweight conservatory, the proposed extension would also result in additional bulk and massing, particularly by increasing the length of the built form and increasing the height with a more solid and extensive roof form linking back to the existing linked extension. Notwithstanding the scale of the proposal to replace an existing conservatory, there would be a harmful impact on openness, both in spatial and visual terms, through the introduction of additional built form and overall massing. However, given the scale of the proposal, this harm to openness would be limited. 11. The Council has also assessed the proposal under Paragraph 154 (g) of the Framework but has concluded that the proposal would not meet the relevant provisions of that paragraph. Contrary to the views of the Council, given the location of the site within a built-up area, albeit with a generally lower density of development than some of the nearby areas particularly to the south, I agree with the Appellant that it would not meet the definition of previously developed land as set out in the glossary to the Framework, and the exception under Paragraph 154 (g) would not apply. Similarly, the proposal would not accord with the provisions of Policy KS3 of the Core Strategy, which in relation to development proposals, refers to those proposed on previously developed land. 12. Even if I were to consider the land as grey belt, the development would not meet all of the criteria set out under Paragraph 155 of the Framework to enable me to conclude that the development before me should not be regarded as inappropriate. The Appellant has also concluded that Paragraph 155 is not applicable to this proposal. 13. Taking all these matters into consideration, I have no doubt that the proposal would be inappropriate development in the Green Belt, with additional, albeit limited, harm due to its impact on openness. It would also fail to conform with Policy H14 of the Local Plan and Policy KS3 of the Core Strategy. Other Considerations 14. Other than in respect of Green Belt grounds, there are no objections to the proposed extension. The design approach would respect the existing design of the main dwelling and preserve the character and appearance of this locally listed building and the landscape setting of the property and the local area, but a high standard of design approach which respects the character and appearance of the host property and of the local area is to be expected in accordance with national and local plan policies. Furthermore, given the scale and siting of the proposal on the northern side of the appeal property, it would preserve the setting of the adjoining Grade II listed property at The Rest, the significance of which is largely derived from its surviving historic and architectural detail as an example of early residential development. However, the absence of any other harm does not provide weight in favour of the proposal but is neutral in my overall assessment. 15. Paragraph 142 of the Framework states that the essential characteristics of Green Belts are their openness and their permanence, and paragraph 145 of the Framework sets out that once established, Green Belt boundaries should only be altered where exceptional circumstances are fully evidenced and justified through the preparation or updating of plans. There is no information before me that such an exercise has been undertaken. The site forms part of the established Southeast Appeal Decision 6010140 4 Dorset Green Belt together with adjoining land and has been so designated to serve Green Belt purposes. 16. I have noted that no objections were raised to the proposal from neighbours or other consultees, but the absence of objections does not add weight in support of the proposal. 17. Although I agree with the Appellant that the site is enclosed by woodland and there are glimpsed views only of the cottage in very short range views, this does not mean that the proposal would not affect the openness of the Green Belt, given that it would add further built development to the existing site. I do not therefore add weight to this contention in favour of the proposal. 18. Whilst I agree that taken on its own the increase in floorspace would be limited, it would add to the overall bulk and massing of the dwelling. Furthermore, the relevant test under the Framework and in particular paragraph 154 c) is in relation to the size of the original dwelling. I have already found that the proposal when taken together with the other extensions and alterations already undertaken would result in a disproportionate increase in relation to the size of the original dwelling. Planning and Green Belt Balance 19. The Framework states that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. It goes on to advise that substantial weight should be given to any harm to the Green Belt and 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. 20. The proposal would be inappropriate development within the Green Belt and there would be additional, albeit limited, harm to openness. In accordance with the Framework, substantial weight should be given to any harm to the Green Belt. Even taken together, the other considerations put forward provide little support for the scheme. Therefore, they do not clearly outweigh the harm to the Green Belt and ‘very special circumstances’ to justify the development do not exist. Therefore, the proposed extension would not accord with the development plan and there are no other material considerations to outweigh that finding. Conclusion 21. For the reasons given above, the proposals conflicts with the development plan as a whole and there are no considerations that would outweigh that conflict, including the Framework. Having regard to all other matters raised, the appeal should not succeed. L J Evans INSPECTOR