Appeal 6003387

The appeal is allowed and planning permission is granted for a single storey rear extension, single and two storey side extension to provide new attached dwelling at side, rear dormer, roof lights in front roof slope, associated cycle and bin storage and car parking, and separate amenity space at [site address] in accordance with the terms of the application, [name]/1857/25, subject to the conditions in the attached schedule.

The description of development on the application form does not include the single storey element of the side extension to form the proposed dwelling. This is clearly shown on the plans before me. Therefore, in my decision, I have used the Council’s description from the decision notice as it more accurately describes the proposed development. I am satisfied that the cases of the main parties would not be prejudiced by using this description.

The Harrow Local Plan 2021-2041 (2026) (the Local Plan) was adopted on 24 March 2026. This now forms part of the statutory development plan and replaces policies of the Harrow Local Plan Core Strategy (2012) (the [name]) and the Harrow Development Management Policies Local Plan (2013), and I have therefore had due regard to this in my decision. The Council has confirmed which policies are most relevant to the decision and both parties have been provided with the opportunity to make representations on these policies.

The main issues are: • the effect of the development on the character and appearance of the appeal site and the surrounding area; • whether the site is a suitable location for the proposal having regard to relevant development plan policies concerning residential development; and • whether the proposal would meet the requirements of [name] (BNG).

The appeal property relates to a 2-storey semi-detached dwelling, and its associated garden and driveway, located in a predominantly residential area. It sits at the end of a curved row of similar dwellings, where most semi-detached pairs are linked by single storey garages. A small area of open space containing several trees lies adjacent to the site. The surrounding area is characterised by 2-storey properties, predominantly constructed of red brick with red tiled roofs, giving a generally uniform appearance, although the mix of semi-detached and terraced dwellings adds some variation and visual interest. Green spaces and trees contribute to a verdant, open character.

The proposal would create a new dwelling by extending [site address] to the side, continuing the front building line and matching the roof slope and height. Although the site is at the end of a row of similar properties, the curvature of the road breaks combined views of these dwellings with the appeal property. The site is also viewed in the context of properties with longer frontages, located to the rear of the large open space opposite, and terraced dwellings to the west. Using matching materials to No 37, the proposed dwelling would create a terraced appearance that would not be out of keeping with the character of the area.

The Council’s Residential Design Guide Supplementary Planning Document (2010) (the [name]) advises that 2-storey extensions should have a subordinate roof, be set back from side boundaries and should reflect the pattern of development in the street scene. Whilst the proposal would not be subservient to No 37, and would alter its appearance, it would form a new self-contained dwelling rather than a domestic extension, which is what the guidance addresses. In these circumstances it is appropriate that the new dwelling would read as having equivalent status to No 37. As such, it would not detract from the existing building, and the resulting group of 3 dwellings would reflect the longer frontages found nearby.

Part of the development would extend up to the side boundary and would remove most of the open area next to the existing dwelling, within the site. However, this is currently partly enclosed by the hedgerow along the side boundary, and the adjacent area of open green space provides a clear separation from the junction with [address], maintaining a strong sense of openness at this prominent corner. Consequently, the proposal would not significantly reduce openness or harm the open character and appearance of the area.

The proposed flat roofed rear dormer would be similar in appearance to the dormer at the rear of No 37, which is visible across the open space to the east, although partially screened by trees. Another rear dormer is also visible on a property fronting [address]. The proposed dormer would not be set in from the side wall by 1 metre in line with the guidance in the [name]. Nevertheless, given its rear position and the presence of other dormers in the locality, it would not appear overly prominent or obtrusive, even in combination with the existing dormer. The overall design of the proposed dwelling would be in keeping with surrounding properties, and there is no substantive evidence before me to suggest it would not be of a high design quality.

I therefore conclude that the proposed development would not harm the character and appearance of the appeal site and the surrounding area. It would therefore comply with Policy D3 of the London Plan (2021) (the London Plan) and Local Plan Policy GR1 which, amongst other things, collectively seek to ensure that proposals achieve a high standard of design and layout that respects the character and context of the locality, positively responding to local distinctiveness through their layout, orientation, scale, height, massing and design characteristics.

Policy GR10 of the Local Plan supports development on garden land where it is of high-quality design, of an appropriate scale and intensity for its context, and makes a comprehensive use of land. The policy sets out that housing on individual plots of garden land will not generally be considered comprehensive. The supporting text explains that residential gardens are a strong element of suburban character and an important component of the quality of life for residents. It also highlights that residential properties with individual rear gardens are a predominant characteristic, and the Council discourages ad hoc development to individual rear gardens which can lead to incremental erosion of suburban character.

The site meets the definition of garden land set out in the Council’s Garden Land Development Supplementary Planning Document (2013) (the [name]). I have therefore assessed the proposal on that basis. However, as the [name] relates to policies of the [name] that are no longer in force, the approach to the suitability of developing garden land should be taken from the recently adopted Local Plan.

As established under the first main issue, the proposal would be of high-quality design and of a scale appropriate to its context. It would not be positioned to the rear of an existing dwelling, but would instead continue the established building line, retaining the characteristic layout of houses with individual rear gardens. Both the existing and proposed dwelling at the site would have adequate garden space, and the loss of the side area would not harm the suburban character of the area.

The supporting text to Local Plan Policy GR10 explains that what constitutes a comprehensive development in terms of the number of sites, will be determined on a case-by-case basis and will be assessed by the scale of development and the overall site size. Whilst the policy states that housing on individual plots of garden land will not generally be considered to be comprehensive, there is no evidence before me to suggest that this site could reasonably form part of a larger development.

Local Plan Policy HO3 also supports small housing developments, subject to 4 criteria. It requires that where proposals could contribute to a more comprehensive development, they should demonstrate how delivery will not compromise the remainder of the site. This proposal would make efficient use of a small, clearly defined plot that relates well to the existing built form. It would provide an acceptable design approach, living conditions and parking provision, and appropriate landscaping can be secured by condition. The proposed development therefore complies with Local Plan Policies GR10 and HO3 in addition to London Plan Policy H2, which supports well-designed homes on small sites to help meet London’s housing needs.

Whilst the Council has referred to an appeal decision in respect of its approach to garden land development, this relates to the [name] which has been replaced by the Local Plan. The appeal must be determined in accordance with the adopted development plan and, as set out above, I have found that the proposal would comply with this. In the context of a changed policy the previous appeal decision is of limited relevance. The Council has also referred to Local Plan Policy HO2. However, as this relates to residential conversions into multiple homes, it is not directly relevant to the appeal proposal, and I therefore find no conflict with it.

I conclude that the site is a suitable location for the proposal, having regard to relevant development plan policies concerning residential development.

BNG is required under a statutory framework introduced by Schedule 7A ([name] in England) of the Town and Country Planning Act 1990 (the Act). Under this framework, subject to some exceptions, every planning permission is deemed to have been granted subject to the condition that the biodiversity gain objective is met. This requires development to deliver at least a 10% increase in biodiversity value relative to the pre-development biodiversity value of the on-site habitat. This increase can be achieved through onsite biodiversity gains, registered offsite biodiversity gains or statutory biodiversity credits.

The biodiversity gain condition is a pre-commencement condition, and once planning permission has been granted, a Biodiversity Gain Plan must be submitted and approved by the local planning authority before commencement of the development. The Planning Practice Guidance (the PPG) indicates that it would generally be inappropriate to refuse an application on grounds that the biodiversity gain objective will not be met. However, the PPG also states that decision makers may need to consider more broadly whether the biodiversity gain condition is capable of being successfully discharged.

The appellant’s [name] (September 2025) casts some doubt as to whether the required 10% BNG could be provided on site, specifically in relation to management and monitoring. Nevertheless, the appellant maintains it would be possible with some revisions to landscaping. Even so, the [name] sets out 3 further options to meet the BNG requirements, which are: to purchase offsite biodiversity units; acquire land for biodiversity offsetting; or as a last resort, purchase statutory credits.

It is not necessary for me to make findings on how a future Biodiversity Gain Plan condition will or ought to be discharged. It is sufficient that I am satisfied, in broad terms, that various options exist such that a condition could be discharged and the statutory obligation met. Given the modest scale of the proposal, a planning obligation in these circumstances would be unlikely, but the specific details and associated mechanisms for delivery are matters that would form part of any Biodiversity Gain Plan.

I therefore conclude that the proposal would meet the requirements of BNG and would comply with London Plan Policy G6 and Local Plan Policy GI3. Collectively these seek to ensure that development proposals provide appropriate levels of BNG.

An interested party has expressed concerns that the proposal would be environmentally unfriendly locally and cause parking issues to local residents and those accessing the local school, in addition to the likely tenure of the property. These concerns are largely speculative, and there is no substantive evidence before me to support them. In respect of parking, a space would be provided to the front of both properties, and, given the small scale of the proposal, it is unlikely that it would place significant pressure on existing on street parking provision. Furthermore, the Council has not raised an objection in relation to this matter, and I see no reason to reach a different view.

The Council has recommended a number of planning conditions should the appeal be allowed. I have considered these in the context of the National Planning Policy Framework and the PPG, and amended them where necessary for clarity and to ensure they comply with the relevant tests and legislation, taking into account the appellant’s representations.

In addition to the standard time limit condition, I have imposed a condition requiring development to be carried out in accordance with the approved plans, for the avoidance of doubt and in the interests of certainty.

London Plan Policy D12 requires all development to achieve high standards of fire safety. Although the submitted fire safety form does not relate specifically to a new dwelling, the plans include details of escape routes, fire doors, smoke and heat detectors and a [name]. These measures demonstrate compliance with the policy for a development of this scale and can be secured by condition.

A soft landscaping condition is reasonable and necessary to mitigate the loss of the hedgerow and to protect the character and appearance of the area. The Council’s suggested condition also sought a survey and protection measures for existing trees and hedgerows. However, the [name] confirms the hedgerow would be removed, and the small garden trees observed towards the garden’s boundaries are of limited significance in terms of their amenity value. Requiring protection measures would therefore not be reasonable or necessary. Accordingly, I have reworded the condition to focus solely on the provision and maintenance of a landscaping scheme, combining it with a separate suggested condition.

A condition requiring any hardstanding to be porous or drained to a permeable area is necessary to prevent surface water run‐off. Details of boundary treatments are also required to ensure adequate privacy for both dwellings and to safeguard the character and appearance of the area, including any boundaries to the front and side. A condition securing cycle storage is reasonable and necessary to promote sustainable travel. A condition regarding external materials is necessary to ensure they match the adjoining dwelling and thereby protect the character and appearance of the area, particularly as materials are not specified on the plans.

The Council has suggested a condition which would remove permitted development rights under the Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO) to change the use of the proposed dwelling to a small HMO, citing the need to maintain mixed, balanced, sustainable and inclusive communities and to protect residential and visual amenity. However, no substantive evidence or policy justification has been provided, and such a restriction would not apply to comparable properties in the area. The condition would not therefore be reasonable or necessary.

A restriction on openings in the flank wall of the dwelling would not be necessary to protect living conditions of neighbouring properties. This elevation mostly faces the open space, and the GPDO already requires new first-floor side windows to be obscure glazed and non-opening. The Council has also suggested a condition removing permitted development for alterations and extensions, porches and outbuildings. Given the adequate garden size, the space provided to the front and the contained nature of the rear garden, no compelling justification has been provided to demonstrate that such a restriction is required to protect character, parking or neighbouring living conditions. It would therefore not be reasonable.

The permission would be subject to the mandatory BNG condition, requiring a biodiversity gain plan to be submitted to and approved by the local planning authority prior to commencement of the development. As this is directly imposed by the legislation it is unnecessary to duplicate it.

For the above reasons, having had regard to the development plan as a whole and all other relevant material considerations, I conclude that the appeal should be allowed.

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

The development hereby permitted shall be carried out in accordance with the following approved plans: Location Plan (scale 1:1250); PL – 01 (Block and [name]); PL – 03 (Proposed Site Plan); PL – 04 (Proposed Ground Floor Plan); PL – 05 (Proposed First Floor Plan); PL – 06 (Proposed Loft Plan); PL – 08 ([name]); and PL – 09 (Proposed Section).

Prior to the occupation of the new dwelling hereby permitted, a scheme of landscaping, indicating any trees or hedgerows to be retained, and including planting plans and a schedule of plants, noting species, plant sizes and proposed numbers/densities shall be submitted to and approved in writing by the local planning authority. All planting, seeding or turfing comprised in the approved details of landscaping shall be carried out in the first planting and seeding seasons following the occupation of the new dwelling or the completion of the development, whichever is the sooner. Any trees or shrubs which, within a period of 5 years from the completion of the development, die, are removed, or become seriously damaged or diseased, shall be replaced in the next planting season, with others of a similar size and species.

Prior to the first occupation of the new dwelling hereby permitted, details of cycle storage shall be submitted to and approved in writing by the local planning authority. Details shall include the type and specification of the cycle racks. The cycle storage shall be made available prior to occupation of the new dwelling and shall be retained thereafter.

Prior to the occupation of the new dwelling hereby permitted, details of the positions, height, design, materials and type of boundary treatments to be erected shall be submitted to and approved by the local planning authority. The boundary treatments shall be completed in accordance with the approved details before the new dwelling is occupied and shall be retained as such at all times thereafter.

Prior to the occupation of the new dwelling hereby permitted, the external hard surfacing shall be constructed from porous materials or provision shall be made to direct run-off water from the hard surfacing to a permeable or porous area within the curtilage of the site.

Prior to the occupation of the new dwelling hereby permitted, the fire safety measures identified on the approved plans: PL – 04 (Proposed Ground Floor Plan); PL – 05 (Proposed First Floor Plan); and PL – 06 (Proposed Loft Plan), shall be fully implemented and shall be retained as such at all times thereafter.

The materials used for the external walls and roof of the dwelling hereby permitted, shall match those used on the dwelling at [site address] .