5 Thornton Avenue, Chiswick, London, W4 1QE

1. 3 Feb 2026

   Received by Hounslow

2. 17 Mar 2026

   Decision issued: GRANT

3. 12 Aug 2026

   Added to PlanIndex

Permission has been granted, usually subject to conditions listed on the decision notice, some of which must be discharged before work starts. The decision notice on the council portal sets out exactly what was approved.

Work must normally begin within three years of the decision or the permission lapses. Neighbours cannot appeal a grant; challenging one means judicial review of how the decision was made, within tight time limits.

A lawful development certificate is a legal determination, not a planning judgement. It asks the council to confirm either that existing use or works are lawful, often through the passage of time, or that a proposal would not need planning permission at all. The applicant must prove the facts; the merits of the scheme are not considered.

More on lawful development applications in our guide

• 5 Thornton Avenue, Chiswick, London, W4 1QE

  P/2026/0156 Submitted 19 Jan 2026 0m away

  Erection of a single storey rear and side infill extension to the house.

  Granted Householder Extension 9 docs
  Small domestic

• 17 THORNTON AVENUE, CHISWICK, LONDON, W4 1QE

  P/2021/2219 Submitted 27 May 2021 41m away

  Details submitted pursuant of Condition 6 (construction method statement) and 7 (construction management plan) following planning permission 01122/17/P1 dated 07/09/2020 for enlargement of existing basement including creation of a front light well, replacement of front rooflight and addition of railings to front roof gable.

  Granted Conditions Loft or dormer 6 docs

• 22 THORNTON AVENUE, CHISWICK, W4 1QG

  P/2019/3933 Submitted 29 Oct 2019 56m away

  Erection of a single storey part side and rear extension, erection of a rear outrigger roof extension with increase in height of the chimney stack, installation of replacement double glazed windows to the house

  Refused Householder Extension Windows or glazing 16 docs
  Small domestic

• 132 Chiswick High Road, Chiswick, London, W4 1PU

  P/2025/3419 Submitted 14 Nov 2025 57m away

  Creation of an outdoor seating area with balustrade enclosure to the front of the restaurant with alterations to two of the six front panels to existing shopfront.

  Refused Full applications Windows or glazing 29 docs

• 26 Thornton Avenue, Chiswick, London, W4 1QG

  P/2026/0194 Submitted 21 Jan 2026 66m away

  Erection of single storey side extension and rear extension. Enlargement of the existing basement. Replacing existing windows. Installation of air source heat pump in rear garden. Installation of new fencing on the front boundary. Conversion of the existing two self contained flats to a single family house.

  Granted Full applications New dwelling Extension +1 15 docs
  Small domestic

• 26 Thornton Avenue,Chiswick,London,W4 1QG

  P/2026/1399 Submitted 8 May 2026 66m away

  Certificate of Lawfulness for proposed enlargement of rear roof extension, erection of rear outrigger extension, and installation of two front roof windows.

  Granted Lawful development Extension Windows or glazing 6 docs

• P/2026/2033 Granted

  3 Benedict Drive, Feltham, TW14 8JH

  Certificate of lawfulness for the proposed erection of a rear roof extension with hip to gable conversion with windows to the front and side of the house.

  8 Jul 2026 Lawful development
• P/2026/2027 Granted

  115 Northumberland Crescent, Feltham, TW14 9SP

  Certificate of lawfulness for the proposed erection of a rear roof extension and windows to the front of the house.

  8 Jul 2026 Lawful development
• P/2026/2009 Granted

  3 Brainton Avenue, Feltham, TW14 0AZ

  Certificate of lawfulness for the proposed erection of a rear roof extension and Juliette balcony with front roof windows to the house.

  7 Jul 2026 Lawful development
• P/2026/2014 Granted

  82 Sussex Avenue, Isleworth, TW7 6LB

  Certificate of lawfulness for the proposed erection of a rear roof extension, a porch to the front of the house, and a front roof window.

  7 Jul 2026 Lawful development
• P/2026/2473 Awaiting decision

  16 Somerset Waye, Hounslow, TW5 9HG

  Certificate of lawfulness for the proposed erection of a rear roof extension with two roof windows to the front and alterations to the existing side roof from flat roof to pitched roof.

  1 Sep 2026 Lawful development