Appeal 6002138

The appeal is allowed and planning permission is granted for first floor front to side extension, single storey rear extension, alterations to roof to raise ridge height, roof lights in front and rear roof slopes, alterations to roof of front extension, external alterations (demolition of rear extension), at [site address] [site address] , [address], Harrow [postcode] , in accordance with the terms of the application, [name]/2074/25, subject to the following conditions:

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: Site & [name] – APL-DR-00-00 Proposed Ground Floor Plan – APL-DR-P1-00-10 Proposed First Floor Plan – APL-DR-P1-01-11 Proposed Loft Plan – APL-DR-P1-02-12 Proposed Roof Plan – APL-DR-P1-RL-13 [name] & [name] – APL-DR-P1-XX-14 [name] & [name] – APL-DR-P1-XX-[address] – APL-DR-P1-ZZ-17

The materials to be used in the construction of the external surfaces of the development hereby permitted shall match those used in the existing building.

Following the site visit, the Council informed me that Harrow’s New Local Plan 2021-2041 (the LP) was adopted on 24 March 2026. The Council confirmed that LP Policy GR1 now represents the sole development plan policy relevant to the appeal, and that the policies of the Harrow Development Management Policies (July 2013) and the [name] (February 2012) cited in the decision notice no longer form part of the development plan. I have therefore determined the appeal on this basis. The appellant was given the opportunity to comment on the updated policy position. I am satisfied that no party has been prejudiced as a result.

The main issue is the effect of the proposed development, in particular the first-floor front extension, associated roof alterations and increased roof ridge height, on the character and appearance of the area.

The appeal site forms one half of a semi‐detached pair of mid‐20th-century dwellings that include a prominent central two‐storey projection with bay windows and flanking roof slopes. The parties refer to the incorporation of so‐called “Metroland” characteristics. On the evidence before me, this appears to be a descriptive term used by the Council and in previous appeal decisions to denote the general architectural form of these mid‐20th-century dwellings, rather than a formally defined heritage or policy designation. The site lies within a suburban residential street where many dwellings of originally similar design have been subject to varying degrees of extension and alteration over time.

LP Policy GR1 requires development to achieve a high standard of design that responds positively to local character and context. Whilst it does not require the replication or preservation of existing buildings in their original form, it promotes a design‐led approach that respects character while allowing appropriate change.

From my site visit, I observed that [site address] and nearby streets display a wide variety of extensions and alterations, including front, side and roof‐level additions. While the characteristic Metroland form remains evident, it is clear that much of the original uniformity has been diluted over time, with many properties having evolved in differing ways whilst continuing to make a positive contribution to the streetscape.

A central focus of the Council’s objection is the loss of the catslide roof. [name] acknowledge that this is a traditional feature of Metroland dwellings and that its removal would alter the appearance of the appeal property, that change would not necessarily be harmful. I observed at my visit that many properties in the locality have already lost their original catslide roofs, and that such alterations can be absorbed into the surrounding townscape without undermining its character.

Moreover, the proposal would retain the dominant front projection, which mirrors that of the adjoining dwelling. Consequently, although the roof form would change, the development would retain a key architectural feature that ties the dwelling to its adjoining pair and the wider streetscape. In this context, the loss of a traditional roof form does not, in itself, equate to harm where the overall form and scale of the dwelling would remain legible and consistent with the area’s character.

Although the symmetry of the semi-detached pair is a relevant consideration, it is not an overriding policy requirement and must be assessed in context. I observed many examples locally where symmetry between attached dwellings has been altered. In most cases, this has not resulted in harm where a coherent design approach has been followed.

I place particular weight on the example at No [address], a property of very similar original design where a closely comparable extension has been built. Having viewed that property and the approved plans, the extension appears appropriately scaled and successfully integrated into the host building. Moreover, as with the appeal proposal, it retains the clear central projection to mirror the adjoining property, despite some loss of symmetry. Whilst each case must be determined on its own merits, that example provides a relevant and persuasive indication of how the proposed development would read in practice. Against that benchmark, I am not persuaded that the appeal proposal would appear out of scale or visually intrusive.

I note the provisions of the Residential Design Guide Supplementary Planning Document, Adopted 15 December 2010 (the SPD). This cautions against extensions that dominate the host building or fail to harmonise with existing character but also recognises that site‐specific judgement is required. In this case, although the proposal would alter the original roof form, it would retain key architectural features, would be proportionate in scale, and would reflect a pattern of development already established in the area. Accordingly, I find no conflict against the overall objectives of the SPD.

The Council argues that the proposal fails to overcome the concerns identified in a previous dismissed appeal at the site. However, that decision was made within the context of the proposal then before the Inspector and the evidence available at that time. Having regard to the specific proposal now before me, and the extent and effect of similar alterations evident in the locality, I am satisfied that the current proposal would sit comfortably within its surroundings. I therefore do not find the earlier decision determinative to the outcome of this appeal.

For these reasons, I conclude that the proposed development would not harm the character or appearance of the area and would accord with LP Policy GR1 and the provisions of the SPD, the aims of which have previously been set out. It would also accord with the relevant provisions of the National Planning Policy Framework, which have similar aims.

Conditions requiring the development to commence within the statutory time limit and to be carried out in accordance with the approved plans are necessary to provide certainty and ensure compliance with the development plan. A condition requiring the external materials to match those of the existing building is necessary to safeguard the character and appearance of the area.

For the reasons given above, I conclude that the proposed development would accord with the development plan, and there are no material considerations to indicate that the appeal should be determined other than in accordance with the plan. I therefore conclude that the appeal should be allowed and planning permission granted subject to the conditions listed in my formal decision.