Appeal 3374839

The appeal is dismissed.

The Council has submitted the London Borough of Harrow Local Plan 2021-2041 (the Emerging Local Plan) for examination. I am uncertain whether the policies of the emerging local plan are subject to outstanding objections or whether they might change before formal adoption. Consequently, I attach only limited weight to the emerging policies in my assessment.

The main issues are the effect of the proposed development on • the character and appearance of the area with particular regard to whether it would preserve or enhance the character or appearance of the [site address] Conservation Area; and • surface water flood risk.

The appeal site comprises a part single, part two-storey detached dwelling with a detached garage. The house is brick-built with white painted timber cladding on the upper floor and a concrete tiled roof. It has an A-Framed design with existing roof extensions.

It sits within a prominent corner plot located at the junction of [site address] and Runnelfield, with its primary elevation facing onto Runnelfield, a small development of 1970s properties and its side elevation and outbuilding facing onto [site address] . [site address] slopes down and the property sits below street level, particularly the rear garden. There are a number of mature trees within the appeal site, protected by Tree Preservation Orders1. The site and its surroundings are characterised by a spacious and verdant character.

The appeal site is located with the [site address] Conservation Area (the CA). Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 requires special attention to be paid to the desirability of preserving or enhancing the character or appearance of the conservation area.

The significance of the CA is primarily derived from its variety of late Victorian and Edwardian buildings on [site address] , complemented by a distinctive green streetscape and later buildings which were built between 1910 and 1930 inspired by the [name] ideal. The area is characterised by spacious plots, quality streetscape, and a tranquil and private environment. The appeal site, although the only building on Runnelfield to be included with the CA boundary, exhibits many of these characteristics with its spacious and verdant corner plot location. However, the appeal property itself is a 1970’s-built chalet bungalow and is identified as a building which could be enhanced.

The proposal would involve a number of extensions and alterations to the host property. The Council has raised no objection to the proposed replacement porch and the alterations to the roof of the side extension to raise its height by 0.4m. Based on the evidence before me and my own observations, I see no reason to disagree with these conclusions. The proposal would also involve the demolition of the existing rear extension. This would not result in the loss of any historic fabric or architectural features which are of significance to the CA. Thus, it would preserve the character and appearance of the CA.

The development further comprises a single and two-storey side extension to the rear of the host property. The Council has raised no specific concerns in relation to the single storey elements. However, they have raised concerns in relation to the two storey elements which include the enlargement of the existing dormer window and the extension of the gable by approximately 1.5 metres.

These extensions would be visible when viewing the host property within the surrounding area, particularly from Runnelfield. [name] acknowledge that the elevation faces away from the CA, and would retain the setback from the eaves, the dormer extension would be visually dominant, disrupting the symmetry and proportions of the existing roof form. This, together with the extended gable would result in a visually unbalanced and bulky form of development that would be at odds with the character of the host property and surrounding area.

The proposal would also involve a further single storey extension to provide a link between the main house to the detached outbuilding. The Harrow Residential Design Guide Supplementary Planning Document (the SPD) states that any linking elements between the main dwelling and the outbuilding must be modest in scale and clearly subordinate to the host building. 1 [name]: A1-48 and T001, T004, T005 and T006

The proposed link would erode the site’s openness and undermine the garden suburb character of the CA, causing harm to its significance as a heritage asset. Although partly screened by a boundary wall, the extension would introduce built form into an area that currently contributes to the CA’s spacious quality, resulting in a harmful loss of openness.

The proposal would also involve the enlargement of an existing dormer window on the ‘west elevation’ alongside the replacement of the roof tiles. The Residential Design SPD 2010 states that dormer windows must be modestly scaled, set in from the eaves and should not dominate the roof slope. The Council has raised no concerns in relation to the replacement on the roof tiles, subject to further details regarding materials being provided and subsequently approved and I see no reason to disagree.

However, the proposed enlarged dormer would be significantly larger in both width and height, resulting in an addition which would be dominant and appear disproportionate in relation to the roof slope. Accordingly, the scale and prominence of the dormer extension would undermine the architectural character of the host building and erode the visual harmony of the streetscape causing harm the character and appearance of the area and the CA.

The proposal would also involve the installation of roof lights, including within the elevation facing onto [site address] . The submitted plans show that these would protrude above the roof slope. As such, these would appear visually intrusive and at odds with the prevailing character of the area which comprises of simple and largely uninterrupted roof profiles.

The appellant states that the rooflights and dormer extensions would make a significant difference to the quality of the bedroom spaces, which are otherwise constrained by the a-framed design. However, it has not been demonstrated that these benefits could not be achieved with an alternative and less harmful proposal.

In respect of the proposed gates, these would enclose an area which is already hard surfaced and used for parking directly in front of the garage. At my site visit I observed that gates and boundary treatments such as this are not uncommon on this part of [site address] . Furthermore, the gates would be located between the existing high boundary wall, and as a result would not lead to a harmful reduction to the open, verdant character of the area.

The submitted plans show that the existing timber cladding would be replaced with natural cedar cladding. However, the Council have stated that the replacement of the timber cladding would only be acceptable if the timber was painted white to match the existing timber cladding and that which is commonly found in the local area. The appellant has indicated that they are agreeable to this, and I am satisfied that this could be dealt with by imposing suitably worded planning

Whilst there is no objection in principle to the replacement of the existing windows and doors, a new doorway and Juliette balcony, the appeal is not supported by any substantive details of the windows and doors which are to be used. Nonetheless, I am satisfied that these details could be required by condition and further details to be submitted and approved by the Council prior to installation.

The Council has also raised no objection in principle to the provision of a raised patio with balustrade at the rear of the property. However, they do raise concerns regarding the type of materials to be used. However, I am satisfied that this could be addressed by imposing suitably worded planning conditions.

For the above reasons, whilst I have found that some elements of the proposal would not individually cause harm to the character and appearance of the area, I conclude that the proposed development, by infilling the garden space to create a single-storey link, together with the increased built form and associated alterations, including enlarged dormers, would cumulatively cause harm to the character and appearance of the area and would significantly erode the verdant, open qualities of the appeal site. These changes would undermine the spacious, low-density character that is important to the significance of the wider CA, resulting in harm to the designated heritage asset.

Paragraph 212 of the National Planning Policy Framework (the Framework) advises that when considering the impact of development on the significance of designated heritage assets, great weight should be given to their conservation. The Framework advises that any harm to the significance of a designated heritage asset should require clear and convincing justification, and that great weight should be given to the asset’s conservation, irrespective of the level of potential harm.

Given the scale of development, the proposal would cause less than substantial harm to the significance of the CA which would be at the lower end of the scale. Paragraph 215 of the Framework states that where harm is identified to the significance of designated heritage assets and their setting, it should be weighed against the public benefits of the proposal. However, no public benefits have been drawn to my attention. As such, I find the harm would not be outweighed by public benefits.

Consequently, the proposal would cause harm to the character and appearance of the area and thus would fail to preserve or enhance the character or appearance of the CA. Therfore, the proposal would conflict with policies HC1 C and D3 D.1 and D.11 of the London Plan (2021), Policy CS1.B of the [name] (2012) and Policies DM1 and DM7 of the Development Management Policies Local Plan (2013), which seek amongst other things to ensure that new development achieves a high standard of design and layout, responds to local distinctiveness, and seeks to secure the preservation, conservation or enhancement of heritage assets. There would also be conflict with emerging Local Plan Policies GR1, GR6 and HE1(d)(a).

The appeal site is located within located within [name] 1, representing the lowest risk of flooding from rivers and the sea. However, it is within [name] 3b (High) and 3a (Medium), which is categorised as a high-risk location for surface water flooding.

Paragraph 181 of the National Planning Policy Framework (the Framework) sets out that when determining any planning applications, local planning authorities should ensure that flood risk is not increased elsewhere and that where appropriate applications should be supported by a site-specific flood-risk

Policy DM9 of the Harrow Development Management Policies Local Plan, dated July 2013 (DMP) states that proposals requiring a flood risk assessment must demonstrate that the development will be resistant and resilient to all relevant sources of flooding including surface water. It further states that proposals that would fail to make appropriate provision for flood risk mitigation, or which would increase the risk or consequences of flooding, will be refused. Policy DM10 of the DMP states that proposals that would fail to make adequate provision for the control and reduction of surface water run-off will be refused.

The proposal was supported by a Flood Risk Assessment and [name] Strategy2 (the FRA). This document sets out a range of mitigation measures to ensure that the development would be made safe from the risk of flooding. However, the Council’s Drainage Team has objected on the basis that the proposed development would increase the development footprint on the site, thereby increasing surface water flood risk. They further state that provision of [name] (CFS) is required and insufficient information has been provided.

Paragraph 4.5 of the supporting text to Policy DM9 of the DMP states that rainwater falling onto impermeable surfaces such as buildings and hard surfaces has traditionally been disposed of via Harrow’s surface water drainage network. However, with the incremental urbanisation of the Borough and finite drainage network capacity there has said to have been increasing incidence of surface water flooding in recent years.

The proposed development would extend the footprint of the dwelling and as a result the extent of non-permeable surfaces within the appeal site. Whilst the FRA indicates that this increase would be just 4%, there would nevertheless be an increase. The FRA also states that the removal of the western section of wall along the driveway would remove an existing obstruction to the surface water flow route, and surface water would be directed to the rear of the site and away from the proposed development. However, no CFS would be provided and although the plans indicate the removal of an existing wall which could be considered a betterment, the proposal involves the provision of new solid, tall gates which may also act as an obstruction the flow of surface water.

Therefore, whilst I consider that the proposed measures to safeguard the development from flooding could reasonably be secured by condition, without any further information relating to matters of displaced floodwater, I cannot be certain that the proposal would not increase the risk of flooding elsewhere.

For these reasons, I conclude that it has not been demonstrated that the proposed development would ensure that it does not increase the risk of flooding elsewhere. Thus, it would fail to comply with Policy CS1 of the [name] (adopted February 2012) and Policies DM9 and DM10 of the DMP and emerging Local Plan Policy CN3, which require amongst other things, all development to be resistant and resilient to all relevant sources of flooding including surface water and not to increase the risk of flooding elsewhere. 2 Prepared by STM Environmental dated 10 April 2025

I acknowledge that there are works proposed which I have found would not harm the CA. However, the proposal represents a comprehensive suite of works. Therefore, given the number of works which I have found to be unacceptable, requiring amendments or additional information to be provided, and my findings in relation to surface water flood risk, I conclude that it would not be appropriate to issue a split decision.

For the reasons set out above, the proposed development would conflict with the development plan taken as a whole. There are no material considerations, including the Framework, of sufficient weight which indicate a decision should be made other than in accordance with it. Therefore, the appeal should be dismissed