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Planning application

43 William Mews London SW1X 9HQ

Granted Westminster 25/09117/FULL Full Planning Permission Application

Works: Extension Loft or dormer

Permission granted. Work must normally begin within three years of the decision or the permission lapses.

Proposal

Erection of an infill extension at ground and first floor rear replacing the existing first floor enclosed balcony and the ground floor undercroft; installation of new rooflight on main roof.

As published by the council, reference 25/09117/FULL

Application record

Reference
25/09117/FULL
Type
Full Planning Permission Application
Status
Decided
Decision
Granted As published: Application Permitted
Received
17 Dec 2025
Validated
23 Jan 2026
Decided
31 Mar 2026
Ward
Knightsbridge & Belgravia
Decision by
Delegated Decision
Postcode
SW1X 9HQ

Timeline

Dates from the published record

  1. 17 Dec 2025

    Received by Westminster

  2. 23 Jan 2026

    Validated

    Checked as complete and ready for consideration.

  3. 31 Mar 2026

    Decision issued: Application Permitted

  4. 20 Jul 2026

    Added to PlanIndex

Who's behind it

Company information only, from the register and Companies House

Maddox Planning Ltd Agent, a planning consultancy

119 applications on PlanIndex · across 22 councils · 89% granted

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Documents

Plans, drawings, consultee responses and the officer's report

13 documents on file for this application

A planning file usually holds the application form, drawings and site plans, consultee responses, the officer's report and the decision notice.

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What this grant of permission means

Westminster granted permission on 31 March 2026, subject to any conditions on the decision notice. Work must normally begin within three years or the permission lapses. More in our guide to what happens after a planning decision.

About full applications

A full application seeks permission for a complete, detailed proposal in one go, with siting, design, access and landscaping all fixed at this stage. More in our guide to planning application types.

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