Demolition of existing conservatory and construction of part single, part two storey side and rear extensions

Appeal Decision Site visit made on 9 March 2026 by T Bennett BA(Hons) MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 20 March 2026 Appeal Ref: 6003292 77 Park Lane, Harefield, Hillingdon UB9 6BL • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Crinage against the decision of the Council of the London Borough of Hillingdon. • The application Ref is 9443/APP/2025/2155. • The development proposed is demolition of existing conservatory and construction of part single, part two storey side and rear extensions. Decision 1. The appeal is allowed and planning permission is granted for demolition of existing conservatory and construction of part single, part two storey side and rear extensions at 77 Park Lane, Harefield, Hillingdon UB9 6BL in accordance with the terms of the application, Ref 9443/APP/2025/2155, subject to the following conditions: 1) The development hereby permitted shall begin not later than three years from the date of this decision. 2) The development hereby permitted shall be carried out in accordance with drawing nos 1.2 proposed plans,1.3 location and block plan and 11808-D- AIA tree plan, except in respect of the laurel hedge shown on plan 11808-D- AIA. 3) Prior to commencement of any works above ground level, details of all external facing materials of the extension hereby approved shall have been submitted to and approved in writing by the local planning authority. The development shall be carried out in accordance with the approved details. 4) No development shall commence above ground level until a full specification of all proposed trees to replace those to be felled and hedge planting has been submitted to and approved in writing by the local planning authority. The specification shall include the quantity, size, species, and positions or density of all trees/hedging to be planted. The tree/hedge planting shall be carried out in accordance with the approved specification. 5) All planting comprised in the approved details of tree and hedge planting shall be carried out in the first planting season following the completion of the development, whichever is the sooner; and any trees or hedge, 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. Appeal Decision 6003292 2 Preliminary Matter 2. The description of development in the heading above has been taken from the planning application form. This differs from the Council’s decision notice, however, neither of the main parties has provided written confirmation that a revised description of development has been agreed. Accordingly, I have used the one given on the original application in my decision. Main Issue 3. The main issue is the effect of the proposed development upon the character and appearance of the host property and the locality; with special attention to the Harefield Village Conservation Area (CA). Reasons 4. The appeal property lies within the CA. I am therefore required to pay special attention to the desirability of preserving or enhancing the CA, in accordance with the statutory duty as set out in Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990. 5. I consider the significance of the CA to be derived, in part, from the historic core of the village, characterised by its mix of buildings of architectural and historic interest and use of traditional materials, complemented by its verdant character, established by the mature trees prevalent along the roadsides and around the edges of the open spaces, including village green and sports fields. These elements all contribute positively to the CA’s rural setting and village aesthetic. 6. While not listed, the appeal property is a historic building. The front elevation is set back from the highway behind a driveway. A flat roof garage is located forward of the front elevation, but to the side of the property. Although the property has undergone previous extensions, it remains modest in scale. Through the use of traditional Flemish bond brickwork, sash windows, a clay tiled roof and a distinct steep gabled roof form, the building makes a positive contribution to the special interest and significance of the CA. 7. A part-single, part-two-storey side and rear extension was approved in 2024 but has not been constructed. Whilst this proposal seeks to retain many of the previously approved elements, it also introduces an additional single-storey flat- roof side extension. The Council considers that, due to the design and scale of the additional element, the development as a whole would appear disproportionate and constitute an incongruous addition to the host dwelling. 8. Although the flat roof and lantern of the proposed side extension would contrast with the pitched roof of the host dwelling, appearing more modern in appearance, it would be tempered by the raised parapet and corbelled brickwork. Furthermore, the design largely reflects that of the previously approved single storey rear extension, which was also of a flat roof design. The shape of the glass roof lantern on the side extension reflects elements of the existing gabled roof and dormers, and the use of matching brickwork and sash windows on the front elevation ensures the extension would appear as visually cohesive addition to the host dwelling. 9. The two-storey side extension would be set substantially back from the original front elevation of the host property. The single-storey side extension would be set Appeal Decision 6003292 3 back further still, and would be of limited height, due to it being partially sunken. Furthermore, given the significant setback of the flat roof side extension and screening provided by the existing double garage, the single storey side extension and roof lantern would not be highly conspicuous within the streetscene. 10. Although the proposed side extension would be wide, exceeding the width threshold for side extensions in Policy DMHD1 of the Hillingdon Local Plan: Part Two - Development Management Policies (2020) (LP2), the staggered setbacks effectively break up the massing of the front elevation. This, combined with the limited height of the single storey side extension, ensures that the proposal as whole would remain a subordinate addition to the historic core of the host dwelling, and would not erode the architectural integrity of the original property or its contribution to the CA. 11. Given the combination of the above factors, including use of matching materials, roof form, height and setback, the proposal as a whole would not appear as a disproportionate and incongruous addition to either the host property or within the street scene. 12. As the aim of Policy DMHD1, in relation to the width of side extensions, is to ensure that extensions do not visually dominate the host dwelling and remain subordinate to the original house, given my findings above, I find no harm would arise and it would accord with the overall policy aim. 13. To accommodate the proposal, several category C trees, identified as ranging from low-to-moderate visual quality would have to be felled, along with some pruning of other trees in the rear garden. Whilst these contribute to the general sense of verdancy, they are located to the rear of the existing property and are not highly conspicuous from the street or wider CA. Therefore, I consider the loss of these trees would not have an adverse effect on the verdancy of the CA as a whole and thus their loss would not erode the significance of the CA or have a harmful effect on its character and appearance. 14. Notwithstanding the above, Policy DMHB14 of LP2, amongst other matters, seeks development to retain trees. I am satisfied that there is ample space within the large plot at the rear of the property, for compensatory tree planting to ensure the areas verdancy can be maintained. This can be secured via a suitably worded planning condition, which could also address the Council’s concern regarding the non-native hedging planted adjacent to the front boundary wall. 15. In conclusion, I find that the proposal would not harm the character and appearance of the host property or the significance of the CA, with the character of the CA being preserved. It would therefore accord with Policy BE1 of the Hillingdon Local Plan: Part One - Strategic Policies (2012), Policies DMHB 1, DMHB 4, DMHB 11, DMHB 12 and DMHD 1 of the Hillingdon Local Plan: Part Two - Development Management Policies (2020) (LP2), and Policies D3 and HC1 of the London Plan (2021). These, among other matters, seek high quality design that integrates well with the surrounding area and that preserves or enhances the area, including conservation areas, making a positive contribution to local character. It would also accord with Policy DMHB 14 of LP2 which seeks landscaping enhancements. Appeal Decision 6003292 4 Conditions 16. It is necessary to specify the approved plans as this provides certainty. To ensure no adverse effects to the character and appearance of the host dwelling and CA, it is necessary that samples of external materials are approved. For the same reason, a condition requiring a planting scheme is necessary as is a condition requiring replacement planting in the event any should die or become damaged. Conclusion 17. For the reasons given above the appeal should be allowed. T Bennett INSPECTOR