Appeal 3328560

The appeal is dismissed.

The main issue is the effect of the proposed development on the character and appearance of the host dwelling and surrounding area, including the Ickenham Village Conservation Area (CA).

The CA covers a large area of Ickenham. The non-statutory Ickenham Heritage and Character Assessment identifies the site to be within the Ickenham Metroland Character Area. This part of the CA comprises of a largely residential townscape with a variety of interwar suburban developments which tend to display a uniform scale with an ordered plot layout and clear building lines resulting in a coherent street pattern. Properties on some individual roads also display a diverse vernacular that gives variety and texture to its uniform scale.

[address] comprises of two main original house designs. Those like the appeal property, display a hipped main roof, with a gable on one side which is set well back from the front elevation such that it is less apparent in the street scene. This house type has a distinctive narrow two storey elevation fronting the road, with a projecting flat roof garage to the front. The other main distinctive house design has a simple front gable, with a projecting single storey flat roof garage to the front. Some of the dwellings have single storey extensions to the side. Whilst there is some variation in terms of plot width, most are relatively narrow. The street scene displays a strong sense of uniformity and rhythm, in terms of the design of dwellings, spacing and consistent building lines.

Therefore, whilst [address] is a more recent post war cul-de-sac compared to most of the roads in the CA, it is nonetheless reflective of the CA in terms of its uniform, planned suburban layout.

The appeal proposal is for a part single storey, part two storey side extension, following the demolition of existing extensions. The Council confirm that the proposal complies with the specific guidance for two storey side extensions set out in Policy DMHD 1 of the Hillingdon Local Plan Part Two – Development Management Policies (2020) (LP2). However, Policy DMHD 1 also requires (amongst other things) that all extensions in Conservation Areas are designed in keeping with the original house, in terms of layout, scale, proportions, roof form, window pattern, detailed design and materials.

The proposed two storey extension would be set back from the main two storey front wall of the dwelling by 1 metre, as required by Policy DMHD 1. However, given the very distinctive design of the dwelling, with its narrow frontage width, in my view, a set-back of 1 metre would be insufficient to ensure that the extension would not compete visually with the host dwelling. The mono-pitch roof above the single storey element of the extension would also not sit comfortably with the design of the dwelling, with its distinctive protruding flat roof garage.

Moreover, I consider that the large crown roof would be out of keeping with the roof forms displayed along [address] and would be an incongruous feature that would further accentuate the bulk and mass of the extension. Consequently, I consider that the proposed extension, due to its siting, design, size and scale, would detract from the original form of the host dwelling and would be harmful to its character and appearance.

I have had regard to the wider width of the appeal site and that of [address] together with the subsequent wider spacing between Nos 10 and 12. However, the appeal property forms part of a row of very similar dwellings and I consider that the proposal would, by virtue of its additional width together with its prominence and inappropriate design, interrupt the uniformity and the rhythm of street scene, resulting in harm to the character and appearance of the area.

The statutory duty in Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (the Act) is of considerable importance and weight. Paragraph 197 of the National Planning Policy Framework (2023) (the Framework) states, amongst other things, that the desirability of new development making a positive contribution to local character and distinctiveness should be taken into account in determining applications. Paragraph 199 of the Framework also advises that when considering the impact of development on the significance of designated heritage assets, great weight should be given to their conservation.

For the above reasons, I find that the proposal would have a negative effect on the significance of a designated heritage asset and would result in “less than substantial” harm in the words of the National Planning Policy Framework. No significant public benefits have been put forward to weigh against this harm.

I therefore conclude that the proposal would be harmful to the character and appearance of the host dwelling and would fail to preserve or enhance the character and appearance of the CA. Accordingly, the proposal would be contrary to Policies BE1 and HE1 of the Hillingdon Local Plan: [name] – [name] (2012), [name] 1, DMHB 4, DMHB 11 and DMHB 12 of the LP2, Policies D1, D3, D4 and HC1 of the London Plan (2021) and the Framework. Collectively, and amongst other things, these policies seek to secure a high quality design for new development which positively contributes to local distinctiveness and ensures the conservation or enhancement of the historic environment.

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