Planning application
Flat 1D Block 1 Portman Mansions Chiltern Street London W1U 5AJ
Works: Windows or glazing
Permission granted. Work must normally begin within three years of the decision or the permission lapses.
Proposal
Replacement of single glazed timber sash and casement windows with double glazed timber windows at ground floor level.
As published by the council, reference 25/08576/FULL
Application record
- Reference
- 25/08576/FULL
- Type
- Full Planning Permission Application
- Status
- Decided
- Decision
- Granted As published: Application Permitted
- Received
- 24 Nov 2025
- Validated
- 24 Nov 2025
- Decided
- 30 Apr 2026
- 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.
-
25/05866/FULL Refused
Flat 1D Block 1 Portman Mansions Chiltern Street London W1U 5AJ
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.
Timeline
Dates from the published record
-
24 Nov 2025
Received by Westminster
-
30 Apr 2026
Decision issued: Application Permitted
-
4 Aug 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
133 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
11 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 grant of permission means
Westminster granted permission on 30 April 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.
Nearby applications
Within 0.3 miles
-
Flat 1D Block 1 Portman Mansions Chiltern Street London W1U 5AJ
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.
Refused Full applications Windows or glazing 13 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
2 x Shrub/Trees ? Reduce in height and lateral spread by 1-2 metres ? back to previous.
Withdrawn Trees 6 docs -
Marylebone Road London
The installation of 1 no. 4G/5G cell antenna upon the existing Street Lamp unit. installation of 2 no. radio units upon the existing Street Lamp unit. The installation of 1 no. BBU upon the existing Street Lamp unit and associated ancillary equipment on Marylebone Road.
Decided Telecoms -
Marylebone Road London
Installation of 1 no. 4G/5G cell antenna upon the existing Street Lamp unit. Installation of 2 no. radio units upon the existing Street Lamp unit. Installation of 1 no. BBU upon the existing Street Lamp unit and associated ancillary equipment. Works to be undertaken at Park Crescent Gardens, Marylebone Road, Marylebone, London, W18 1PE.
Decided Telecoms
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