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149 Herlwyn Avenue Ruislip

19188/APP/2025/3239FullRefused

Refused on 20 March 2026

3 reasons for refusal

Approximate site (title boundary)
Boundary © HM Land Registry, © Ordnance Survey · details

This information is subject to Crown copyright and database rights 2026 and is reproduced with the permission of HM Land Registry. The polygons (including the associated geometry, namely x, y co-ordinates) are subject to Crown copyright and database rights 2026 Ordnance Survey AC0000851063. Conditions of use.

Proposal

Erection of rear extension, hip-to-gable roof conversion and rear dormer, and conversion of property from Class C3 (dwellinghouse) to Class C4 (small HMO) for up to 6 persons (Part retrospective application).

Received
23 December 2025
Ward
RUISLIP MANOR 2022
  1. Received23 Dec
  2. Validated23 Dec
  3. Consult.27 Jan
  4. Target17 Feb
  5. Decided20 Mar

Decided in 87 days (council typically 56)

About this application

This is a full planning application for a dormer extension at 149 HERLWYN AVENUE RUISLIP. Hillingdon has handled 4,983 applications of this type. This one was decided in 87 days, 4 weeks longer than Hillingdon's typical decision time. There have been 2 other applications at this address. In the past year there have been 79 applications across RUISLIP MANOR 2022. We hold 773 applications in total for the HA4 postcode area.

87% of full applications at London Borough of Hillingdon were approved. Across all application types, the council typically decides in about 8 weeks (median).

Based on decided applications received in the last 3 years.Planning something similar? See what gets approved on your street

Why it was refused

  1. The proposed development, by virtue of the number of potential occupants and proposed use, would represent an over-intensification of the site which would be harmful to the amenities of the neighbouring properties and at odds with the established character of the surrounding locality. The proposal would have an unacceptable and undue impact on existing residential amenity in terms of noise and disturbance, over and above what would be expected for a single family dwelling. As such, the proposal would therefore be contrary to Policy EM8 of the Hillingdon Local Plan - Part 1: Strategic Policies (2012), Policies DMH 5 and DMHB 11 of the Hillingdon Local Plan: Part 2 - Development Management Policies (2020) and Policy D14 of the London Plan (2021).
  2. The proposed development, by virtue of its layout, internal design and number of potential occupants, would fail to provide adequate communal space and facilities for the future occupiers. As such, the proposed development would provide a sub-standard and unsatisfactory level of internal living accommodation, contrary to Policy DMH 5 of the Hillingdon Local Plan: Part Two - Development Management Policies (2020) and Policies D3 and D6 of the London Plan (2021).
  3. In the absence of any submitted details or evidence with regard to the level of present on-street parking demand within the locality and whether any spare capacity exists which could satisfactorily accommodate the potential parking displacement generated by the proposed level of occupancy, it is considered that the proposal has the potential to lead to undue on-street parking displacement to the detriment of parking capacity and safety on the local public highway, As such, the proposal would be contrary to Policies DMT 1, DMT 2 and DMT 6 of the Hillingdon Local Plan: Part Two - Development Management Policies (2020) and Policy T4 of the London Plan (2021).

From the council's decision notice.

Application details

Postcode
HA4 6HF
Application type
Full
Scale / size
Small

Planning application dates

Date validated
23 December 2025
Neighbour consultation start
6 January 2026
Last date for comments
27 January 2026
Target decision date
17 February 2026

Applicant and agent

Agent address
Mr David Eagle 23 Northfield Rd london N16 5RL

Planning decision

Statutory period
56 days

Additional information

Documents
4

Site constraints

Checking the site
2/3
Council recordsAppealsFlood risk

Designations that overlap or adjoin the site outline.

  • Article 4 direction: Residential extensions
  • Flood zone 1: Low probability (rivers and sea)

Possibly incomplete for this council: tree preservation orders.

Also checked, none recorded (22)

flood storage areas, conservation areas, listed buildings, green belt, scheduled monuments, World Heritage Sites, World Heritage Site buffer zones, registered parks and gardens, registered battlefields, Heritage at Risk entries, nutrient neutrality catchments, national parks, National Landscapes, SSSIs, Special Areas of Conservation, Special Protection Areas, Ramsar sites, ancient woodland, national nature reserves, local nature reserves, heritage coasts and brownfield registers.

A guide only, from official open data; it is not a planning search. Flood zones cover rivers and sea, not surface water.

Data © Crown copyright and others · sources and licences

Contains public sector information from planning.data.gov.uk (MHCLG and local planning authorities), licensed under the Open Government Licence v3.0. © Crown copyright and database right 2026.

© Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026. The Historic England GIS Data contained in this material was obtained on 2026-11-03. The most publicly available up to date Historic England GIS Data can be obtained from HistoricEngland.org.uk.

© Natural England copyright. Contains Ordnance Survey data © Crown copyright and database right 2026.

© Environment Agency copyright and/or database right 2026. All rights reserved. Flood Map for Planning, Open Government Licence v3.0.

Contains Ordnance Survey data © Crown copyright and database right 2026.

Source: Office for National Statistics licensed under the Open Government Licence v.3.0. Contains OS data © Crown copyright and database right 2026.

Source: Hillingdon

Contains public sector information from the Planning London Datahub, licensed under the Open Government Licence v3.0.

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