Planning application
Flat 1D Block 1 Portman Mansions Chiltern Street London W1U 5AJ
Works: Windows or glazing
Refused. Only the applicant can appeal, within the statutory time limit, and a revised scheme can be submitted instead.
Proposal
Replacement of existing single-glazed timber sash and casement windows with double-glazed timber sash and casement windows to match the existing style and opening type. Existing window frames to be retained with no changes to the structural openings.
As published by the council, reference 25/05866/FULL
Application record
- Reference
- 25/05866/FULL
- Type
- Full Planning Permission Application
- Status
- Decided
- Decision
- Refused As published: Application Refused
- Received
- 19 Aug 2025
- Validated
- 1 Sep 2025
- Decided
- 17 Oct 2025
- Ward
- Marylebone
- Decision by
- Delegated Decision
- Postcode
- W1U 5AJ
Site history
Applications at this address on the Westminster register
This site has had 2 applications since 2025: 1 approved, 1 refused.
-
25/08576/FULL Granted
Flat 1D Block 1 Portman Mansions Chiltern Street London W1U 5AJ
Replacement of single glazed timber sash and casement windows with double glazed timber windows at ground floor level.
Timeline
Dates from the published record
-
19 Aug 2025
Received by Westminster
-
1 Sep 2025
Validated
Checked as complete and ready for consideration.
-
17 Oct 2025
Decision issued: Application Refused
-
21 Jul 2026
Added to PlanIndex
Who's behind it
Company information only, from the register and Companies House
Design Extension Agent, a design practice registered in Purley
Active · incorporated 2025 · Purley
132 applications on PlanIndex · across 24 councils · 75% granted
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See their track recordDocuments
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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Open the documentsWhat this refusal means
Westminster refused this application for the reasons on the decision notice; only the applicant can appeal, and refused schemes often return in revised form. 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.
Nearby applications
Within 0.3 miles
-
Flat 1D Block 1 Portman Mansions Chiltern Street London W1U 5AJ
Replacement of single glazed timber sash and casement windows with double glazed timber windows at ground floor level.
Granted Full applications Windows or glazing 11 docs -
Marylebone Road Public Convenience Opposite Station Approach Marylebone Road London W1U 5AJ
88% historically approved · decision due ~6 Jan
Change of use from public conveniences (sui generis) to a flexible retail/cafe (Class E(a), restaurant (Class E(b), gym (Class E(d) or gallery (Class F.1) use and existing ground floor accessible WC to be converted to storage space for end use.
Awaiting decision Full applications 39 docs -
Flat 4b Block 4 Portman Mansions Chiltern Street London W1U 6NS
88% historically approved · decision due ~2 Jun
Like for like replacement of nine windows at lower ground floor level.
Awaiting decision Full applications Windows or glazing 11 docs -
Flat 4a Block 4 Portman Mansions Chiltern Street London W1U 6NS
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Withdrawn Trees 6 docs -
Marylebone Road London
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Decided Telecoms -
Marylebone Road London
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Decided Telecoms
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