Appeal 3369283

The appeal is dismissed.

Following the Council’s decision on the original planning application, the Council adopted the Richmond upon Thames Local Plan ‘The best for our borough’ (2024 to 2039) on 7 October 2025 (the Local Plan), becoming the local plan to which I am required to have full regard to in my considerations. Both main parties were asked for and have provided comments on the new local plan as far as relevant to this appeal.

The main issue is the effect on the character and appearance of the appeal dwelling and that of the local area, with reference to the Castelnau Conservation Area (the CA).

The appeal dwelling is a 4 storey late Victorian house, with associated two storey coach house that is set back from the main house. This is connected to the main house at ground level by an earlier link extension that wraps around the front of the coach house. The appeal dwelling has undergone extension and alteration over the years, but retains much of its original architectural expression, presence and details.

The appeal dwelling is located on a street predominantly made up of similarly scaled 19th Century villas, which results in a coherent high quality streetscape. The Castelnau Conservation Area Study and the Barnes Village Planning Guidance (2015) identify the large scale formal townscape of the road of Castelnau as forming the essence of the CA, with a pleasant variety of style and an overall cohesion, through the use of similar materials and bold architectural detailing. As such, it makes substantial contribution to its significance.

The CA is a heritage asset to which I have a statutory duty under section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990. I must pay special attention to the desirability of preserving or enhancing the character or appearance of a Conservation Area.

The Council have included the appeal dwelling in their register of Buildings of [name], which along with its location in the CA, results in it being a Non- Designated Heritage Asset (NDHA), as defined by the provision of the PPG1. I have considered the effect of the proposal in line with paragraph 216 of the National Planning Policy Framework (2024) (the Framework) accordingly.

The proposal is for a first floor flat roofed linking extension that would sit above the previous ground floor link extension between the main house and the coach house. This would be set back from their front elevations and the rear elevation of the coach house but would align with the rear wall of the main house at first floor level. The height of the proposal would result in it overlapping the eaves of the coach house

The proposal would be readily apparent in street views of the appeal dwelling and in longer rear views from surrounding properties. In these views the proposal would appear as a box like brick addition to the appeal dwelling, infilling the first floor separating space between the appeal dwelling and the coach house. This would further exacerbate the effect in this regard of the previous ground floor link extension. The overlapping of the coach house eaves would be apparent in more straight on views and would appear as a misaligned and ungainly design detail that would impinge on the roof form and profile of the coach house.

The box like form and scale of the proposal, along with the overlap with the eaves of the coach house, would result in it appearing as a bulky, poorly massed and incongruous addition, which would fail to reflect the shared architectural expression of the main house and coach house. The further loss of separation between the main dwelling and coach house that would arise from the proposal, would result in the appearance of a single large house, rather than a main house with ancillary coach house. The separation space between the main house and the coach house is an original spatial relationship. Infilling this space at first floor level would further diminish the visual effect of this separation. This would lessen the contribution that this separation makes to the townscape importance of the appeal dwelling, as well as reducing the contribution this makes to the high quality of the local streetscene and the significance of the CA.

For the reasons given above, the proposal would not accord with the design guidance set out in [address] Extensions and External Alterations Supplementary Planning Document (2015), which advises that extensions and alterations should sympathetically complement the existing house and be in character with the neighbourhood, harmonise with the original appearance, and not result in the significant reduction of an existing important space or gap between neighbouring buildings. 1 Ref: Planning Practice Guidance: [name] (2014) (as amended)

From my site visit it was apparent that earlier extensions and alterations to buildings that line Castelnau have had a detracting effect on the original appearance of their host buildings and area, most notably to the neighbouring property at 14 Castelnau. The existing front link extension, due mostly to its infilling of the space between the main house and the coach house, is also a detracting feature both to the character and appearance of the appeal dwelling and the CA. Planning and heritage policy and practice develop over time, and these would have been considered at the time of their approval on their own merits. I have done likewise in my consideration of the appeal proposal, which is a main tenet of the planning system. Existing harm to the character and appearance of the appeal dwelling and that of the CA does not justify further harm in this instance.

The appellant has brought my attention to an extant and fully implementable planning permission 2, which allows for a mono-pitch roof form with a small footprint to be installed between the rearmost part of the first floor of the main house and coach house. This does not include any additional living space and would be set below the eaves of the coach house. This would have a very limited presence in views of the appeal dwelling from the street and would not result in any significant lessening of the apparent spatial relationship between the main house and the coach house. As such it would result in no significant harm to the character and appearance of the appeal dwelling or that of the CA. As such, I do not find that this is a comparable exemplar for the appeal proposal and have given this limited weight in my considerations.

For these reasons, I find that the proposal would be harmful to the character and appearance of the appeal property, its significance as a NDHA, and the significance of the CA. This would be contrary to Policies 28, 29 and 30 of the Local Plan, which, amongst other matters, collectively seek to ensure that development, including by extension, is of high architectural and urban design quality, relate to existing context, including local character and townscape appearance, conserving both designated and non-designated heritage assets.

I find that the harm to the appeal dwelling as an NDHA would be substantial, although the harm to the CA would be less than substantial. In accordance with the Framework, great weight should be given to the conservation of those heritage assets. The proposal would increase the living space of the appeal dwelling, which is primarily a private benefit in this instance and no substantive public benefits have been brought to my attention. I must give considerable importance and weight to the effect on the significance of the CA and, in addition, significant weight to the effects on the character and appearance of the appeal property as an NDHA. I consider that these benefits do not outweigh the harm I have identified.

For the reasons given, I conclude that the appeal should be dismissed.