Planning application
14 Cavendish Square London W1G 9DB
Works: Loft or dormer Roofing Demolition Windows or glazing
Relates to 25/07887/LBC
Permission granted. Work must normally begin within three years of the decision or the permission lapses.
Proposal
Alterations including; demolition and alteration to roof structure including the installation of mechanical plant to roof valley above and the provision of a new terrace and associates railing and access arrangement (sliding roof light) to the rear of the main roof, removal of fixed rooflight over central stair; removal of stair from third floor terrace to plant zone at main roof level; installation of replacement roof lights at main roof level; refurbishment of main entrance door, installation of replacement security camera system, alteration to the ground and lower ground floor fenestration facing Deans Mews and facing internal lightwell, installation of replacement windows and doors at rear ground fand first floor level facing Deans Mews elevation and within the internal lightwell, removal of render to lightwell, installation of replacement cover and railings to first floor terrace, installation of onsite greening. All in connection with the use of the lower ground, ground, first and second floor level as a not forprofit museum (Class F1) and use of the third floor as residential flat (Class C3).
As published by the council, reference 25/07886/FULL
Application record
- Reference
- 25/07886/FULL
- Type
- Full Planning Permission Application
- Status
- Decided
- Decision
- Granted As published: Application Permitted
- Received
- 30 Oct 2025
- Validated
- 30 Oct 2025
- Decided
- 11 Mar 2026
- Ward
- Marylebone
- Decision by
- Delegated Decision
- Postcode
- W1G 9DB
Site history
Applications at this address on the Westminster register
This site has had 7 applications since 2025: 3 approved, 0 refused.
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26/05855/ADLBC Decided
14 Cavendish Square London W1G 9DB
Details of doors (external) showing adjoining fabric and key details, windows showing adjoining fabric and key details, sliding roof lights above stair leading to roof terrace showing adjoining fabric and key details, works to the vaults, including any tanking and all sides of roof access leading to roof top terrace to be solid not glazed pursuant to conditions 3 (Part 1,2,3 and 6) and Condition 9 of Listed Building Consent dated 11th March 2026 (RN: 25/07887/LBC).
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26/05840/ADFULL Decided
14 Cavendish Square London W1G 9DB
Details of photographs and specification of facing materials; external doors, windows, sliding roof lights, and railings; and all sides of roof access pursuant to conditions 21, 25 and 26 of planning permission dated 11 March 2026 (RN: 25/07886/FULL). (Linked with 26/05855/ADLBC)
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26/05842/ADLBC Awaiting decision
14 Cavendish Square London W1G 9DB
Details of railings showing adjoining fabric and key details, including detailed drawings with historic building commentary of proposals, including decorative schemes to the rooms behind the front facade, hall, principal stair and stair volume and front external light well. This should include fireplaces, decorative joinery, decorative plaster work and floorboards; pursuant to condition 3(part4,7) of Listed Building consent dated 11th March 2026 (25/07887/LBC)
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26/04714/ADLBC Decided
14 Cavendish Square London W1G 9DB
Detailed drawings of the sliding roof lights above stair leading to roof terrace showing adjoining fabric and key details and detailed study and drawings of the roof light over the stair and its relationship to the existing decorative plasterwork pursuant to condition 3 (5) and (8) of listed building dated 11th March 2026 (RN:25/07887/LBC)
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25/07887/LBC Granted
14 Cavendish Square London W1G 9DB
Alterations including; demolition and alteration to roof structure including the installation of mechanical plant to roof valley above and the provision of a new terrace and associates railing and access arrangement (sliding roof light) to the rear of the main roof, removal of fixed rooflight over central stair; removal of stair from third floor terrace to plant zone at main roof level; installation of replacement roof lights at main roof level; refurbishment of main entrance door, installation of replacement security camera system, alteration to the ground and lower ground floor fenestration facing Deans Mews and facing internal lightwell, installation of replacement windows and doors at rear ground fand first floor level facing Deans Mews elevation and within the internal lightwell, removal of render to lightwell, installation of replacement cover and railings to first floor terrace, installation of onsite greening. Internal alteration and refurbishment throughout.
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25/05407/ADFULL Granted
14 Cavendish Square London W1G 9DB
Details of an Operational Management Plan pursuant to Condition 3 of planning permission dated 9th April 2025 (RN: 25/00722/FULL)
Timeline
Dates from the published record
-
30 Oct 2025
Received by Westminster
-
11 Mar 2026
Decision issued: Application Permitted
-
21 Jul 2026
Added to PlanIndex
Related applications
Cases linked to this one on the register
-
25/07887/LBC Granted
14 Cavendish Square London W1G 9DB
Alterations including; demolition and alteration to roof structure including the installation of mechanical plant to roof valley above and the provision of a new terrace and associates railing and access arrangement (sliding roof light) to the rear of the main roof, removal of fixed rooflight over central stair; removal of stair from third floor terrace to plant zone at main roof level; installation of replacement roof lights at main roof level; refurbishment of main entrance door, installation of replacement security camera system, alteration to the ground and lower ground floor fenestration facing Deans Mews and facing internal lightwell, installation of replacement windows and doors at rear ground fand first floor level facing Deans Mews elevation and within the internal lightwell, removal of render to lightwell, installation of replacement cover and railings to first floor terrace, installation of onsite greening. Internal alteration and refurbishment throughout.
2 later applications on the register refer to this one:
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26/05840/ADFULL Decided
14 Cavendish Square London W1G 9DB
Details of photographs and specification of facing materials; external doors, windows, sliding roof lights, and railings; and all sides of roof access pursuant to conditions 21, 25 and 26 of planning permission dated 11 March 2026 (RN: 25/07886/FULL). (Linked with 26/05855/ADLBC)
-
25/07887/LBC Granted
14 Cavendish Square London W1G 9DB
Alterations including; demolition and alteration to roof structure including the installation of mechanical plant to roof valley above and the provision of a new terrace and associates railing and access arrangement (sliding roof light) to the rear of the main roof, removal of fixed rooflight over central stair; removal of stair from third floor terrace to plant zone at main roof level; installation of replacement roof lights at main roof level; refurbishment of main entrance door, installation of replacement security camera system, alteration to the ground and lower ground floor fenestration facing Deans Mews and facing internal lightwell, installation of replacement windows and doors at rear ground fand first floor level facing Deans Mews elevation and within the internal lightwell, removal of render to lightwell, installation of replacement cover and railings to first floor terrace, installation of onsite greening. Internal alteration and refurbishment throughout.
Who's behind it
Company information only, from the register and Companies House
DP9 Ltd Agent
Active · incorporated 2004
2,655 applications on PlanIndex · across 36 councils · 98% granted
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Plans, drawings, consultee responses and the officer's report
150 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 11 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.
Nearby applications
Within 0.3 miles
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14 Cavendish Square London W1G 9DB
Alterations including; demolition and alteration to roof structure including the installation of mechanical plant to roof valley above and the provision of a new terrace and associates railing and access arrangement (sliding roof light) to the rear of the main roof, removal of fixed rooflight over central stair; removal of stair from third floor terrace to plant zone at main roof level; installation of replacement roof lights at main roof level; refurbishment of main entrance door, installation of replacement security camera system, alteration to the ground and lower ground floor fenestration facing Deans Mews and facing internal lightwell, installation of replacement windows and doors at rear ground fand first floor level facing Deans Mews elevation and within the internal lightwell, removal of render to lightwell, installation of replacement cover and railings to first floor terrace, installation of onsite greening. Internal alteration and refurbishment throughout.
Granted Heritage and listed buildings Loft or dormer Roofing +2 150 docs -
14 Cavendish Square London W1G 9DB
Details of an Operational Management Plan pursuant to Condition 3 of planning permission dated 9th April 2025 (RN: 25/00722/FULL)
Granted Full applications 11 docs -
14 Cavendish Square London W1G 9DB
89% historically approved · decision due ~21 Oct
Details of doors (external) showing adjoining fabric and key details, windows showing adjoining fabric and key details, sliding roof lights above stair leading to roof terrace showing adjoining fabric and key details, works to the vaults, including any tanking and all sides of roof access leading to roof top terrace to be solid not glazed pursuant to conditions 3 (Part 1,2,3 and 6) and Condition 9 of Listed Building Consent dated 11th March 2026 (RN: 25/07887/LBC).
Decided Loft or dormer Windows or glazing -
14 Cavendish Square London W1G 9DB
89% historically approved · decision due ~20 Oct
Details of photographs and specification of facing materials; external doors, windows, sliding roof lights, and railings; and all sides of roof access pursuant to conditions 21, 25 and 26 of planning permission dated 11 March 2026 (RN: 25/07886/FULL). (Linked with 26/05855/ADLBC)
Decided Loft or dormer Windows or glazing -
14 Cavendish Square London W1G 9DB
89% historically approved · decision due ~14 Sep
Detailed drawings of the sliding roof lights above stair leading to roof terrace showing adjoining fabric and key details and detailed study and drawings of the roof light over the stair and its relationship to the existing decorative plasterwork pursuant to condition 3 (5) and (8) of listed building dated 11th March 2026 (RN:25/07887/LBC)
Decided Loft or dormer 27 docs -
14 Cavendish Square London W1G 9DB
89% historically approved · decision due ~20 Oct
Details of railings showing adjoining fabric and key details, including detailed drawings with historic building commentary of proposals, including decorative schemes to the rooms behind the front facade, hall, principal stair and stair volume and front external light well. This should include fireplaces, decorative joinery, decorative plaster work and floorboards; pursuant to condition 3(part4,7) of Listed Building consent dated 11th March 2026 (25/07887/LBC)
Awaiting decision
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