14 Cavendish Square London W1G 9DB Data via plota.co.uk

25/07886/FULL - Full Planning Permission Application Approved

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). Data via plota.co.uk

View original council record ↗Last checked

Application progress

✓
Received
30 Oct 2025
✓
Consultation
10 Nov 2025
✓
Approved
11 Mar 2026

Approved on 11 Mar 2026 · Delegated Decision · Last checked 17 Oct 2026

Documents 150

Plans & drawings 123

PDF DEM LOWER GROUND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SOUTH AND NORTH ELEVATION P05 Drawing · 30 Oct 2025 View ↗ PDF DEM GROUND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF DEM FIRST FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SECOND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF DEM THIRD FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF DEM ROOF P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SECTION A P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SECTION B P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SECTION C D P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SECTION E F P05 Drawing · 30 Oct 2025 View ↗ PDF DEM SECTION G H P05 Drawing · 30 Oct 2025 View ↗ PDF EX SOUTH AND NORTH ELEVATION P05 Drawing · 30 Oct 2025 View ↗ PDF EX DEANS MEWS ELEVATION P05 Drawing · 30 Oct 2025 View ↗ PDF EX SITE PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF EX LOWER GROUND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF EX GROUND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF EX FIRST FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF EX SECOND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF EX THIRD FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF EX ROOF P05 Drawing · 30 Oct 2025 View ↗ PDF EX SECTION A P05 Drawing · 30 Oct 2025 View ↗ PDF EX SECTION B P05 Drawing · 30 Oct 2025 View ↗ PDF EX SECTION C D P05 Drawing · 30 Oct 2025 View ↗ PDF EX SECTION E F P05 Drawing · 30 Oct 2025 View ↗ PDF EX SECTION G H P05 Drawing · 30 Oct 2025 View ↗ PDF PR LOWER GROUND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF PR GROUND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF PR THIRD FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF PR LOWER GROUND FLOOR FIRE STRATEGY P05 Drawing · 30 Oct 2025 View ↗ PDF PR GROUND FLOOR FIRE STRATEGY P05 Drawing · 30 Oct 2025 View ↗ PDF PR FIRST FLOOR FIRE STRATEGY P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECOND FLOOR FIRE STRATEGY P05 Drawing · 30 Oct 2025 View ↗ PDF PR THIRD FLOOR FIRE STRATEGY P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOF FIRE STRATEGY P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECTION A P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECTION B P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECTION C D P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECTION E F P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECTION G H P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOF SIGHTLINES STUDY P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECTION C COMPARISON P05 Drawing · 30 Oct 2025 View ↗ PDF PR SOUTH AND NORTH ELEVATION P05 Drawing · 30 Oct 2025 View ↗ PDF PR DEANS MEWS ELEVATION P05 Drawing · 30 Oct 2025 View ↗ PDF PR RCP LOWER GROUND FLOOR P05 Drawing · 30 Oct 2025 View ↗ PDF PR RCP GROUND FLOOR P05 Drawing · 30 Oct 2025 View ↗ PDF PR RCP FIRST FLOOR FLOOR P05 Drawing · 30 Oct 2025 View ↗ PDF PR RCP SECOND FLOOR P05 Drawing · 30 Oct 2025 View ↗ PDF PR RCP THIRD FLOOR P05 Drawing · 30 Oct 2025 View ↗ PDF PR WALL TYPES OVERVIEW P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXTERNAL WALL TYPES P05 Drawing · 30 Oct 2025 View ↗ PDF PR INTERNAL WALL AND LINING TYPES P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOF TYPES OVERVIEW P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOF TYPES P05 Drawing · 30 Oct 2025 View ↗ PDF PR RF ALTERATIONS AND TERRACE DETAILS 1 OF 2 P05 Drawing · 30 Oct 2025 View ↗ PDF PR RF ALTERATIONS AND TERRACE DETAILS 2 OF 2 P05 Drawing · 30 Oct 2025 View ↗ PDF PR RF FRONT ROOF ALTERATIONS AND COURTYARD TERRACE P05 Drawing · 30 Oct 2025 View ↗ PDF PR 1F ROOF DETAILS P05 Drawing · 30 Oct 2025 View ↗ PDF PR FLOOR TYPES OVERVIEW P05 Drawing · 30 Oct 2025 View ↗ PDF PR FLOOR TYPES P05 Drawing · 30 Oct 2025 View ↗ PDF PR CEILING TYPES OVERVIEW P05 Drawing · 30 Oct 2025 View ↗ PDF PR CEILING TYPES P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR ED LG 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR ED LG 05 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR ED G 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR ED 03 02 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR ED 03 03 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR TYPE 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOF P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT DOOR TYPE 02 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW TYPE 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW TYPE 02 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW TYPE 03 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW TYPE 04 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW TYPE 05 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW EW G 06 P05 Drawing · 30 Oct 2025 View ↗ PDF PR EXT WINDOW EW 03 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOFLIGHT RL 03 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOFLIGHT RL 04 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOFLIGHT RL 04 02P05 Drawing · 30 Oct 2025 View ↗ PDF PR ROOFLIGHT RL 04 03 AND RL 04 04 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 02 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 03 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 04 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 05 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 06 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID LG 07 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID G 06 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID G 07 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID 02 02 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID 03 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID 03 02 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR ID 03 03 P05 Drawing · 30 Oct 2025 View ↗ PDF PR INT DOOR TYPE 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR FIRE CURTAIN TYPE 01 P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 01 ARCHIVE PLANT CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 02 AND 03 FCU ENCASEMENT P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG-09 TEAPOINT UNITS P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 10 AND 11 FCU ENCASEMENT AND SHELVING P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 12 REFUSE PLATFORM P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 14 BELOW STAIR CUPBOARDS P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 15 BELOW STAIR CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF PR J LG 16 FRONT LIGHTWELL CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF PR J G 01 J 01 01 J 02 01 RISER CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF PR J G 02 03 J 01 02 03 04 J 02 02 03 04 FCU ENCASEMENT P05 Drawing · 30 Oct 2025 View ↗ PDF PR J G 07 08 J 01 06 CEILING ACCESS PANELS P05 Drawing · 30 Oct 2025 View ↗ PDF SERVICE HALLWAY CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF LOBBY SWITCH PANEL P05 Drawing · 30 Oct 2025 View ↗ PDF FCU CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF LIFT CONTROL BELOW STAIR CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF ENSUITE VANITY UNIT P05 Drawing · 30 Oct 2025 View ↗ PDF BEDROOM SHOE STORAGE P05 Drawing · 30 Oct 2025 View ↗ PDF HALLWAY COAT CUPBOARD P05 Drawing · 30 Oct 2025 View ↗ PDF BEDROOM WARDROBE P05 Drawing · 30 Oct 2025 View ↗ PDF KITCHEN ISLAND P05 Drawing · 30 Oct 2025 View ↗ PDF KITCHEN BACK COUNTER P05 Drawing · 30 Oct 2025 View ↗ PDF MEDIA UNIT WITH FCU ENCASEMENT P05 Drawing · 30 Oct 2025 View ↗ PDF FCU ENCASEMENT P05 Drawing · 30 Oct 2025 View ↗ PDF FCU ENCASEMENT P05 Drawing · 30 Oct 2025 View ↗ PDF PR FIRST FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF PR SECOND FLOOR PLAN P05 Drawing · 30 Oct 2025 View ↗ PDF LOCATION PLAN Location Plan · 30 Oct 2025 View ↗

All documents on the council site ↗

Associated applications 2

Site constraints 11

Grade II* listed: Bridge
List entry 1066306 · The pin is inside its outline · 39 more listed buildings within 150 m (4 Grade II*, 35 Grade II)
Listed building consent is needed for work that affects the special interest of a listed building, inside or out, on top of planning permission. Setting can be a consideration for buildings nearby; there is no fixed radius.
Show the other 39 with distances
Historic England ↗
Harley Street conservation area
Demolition needs planning permission and permitted development is restricted.
The council must give weight to preserving or enhancing the area's character and appearance. Not every council has published its boundaries as open data.
Council document ↗
2 Article 4 directions
Article 4 Basement Development Permitted Rights Removed · Article 4 Direction Class E To C3 In Central Activities Zone. Named permitted development rights are withdrawn here.
An Article 4 direction withdraws particular permitted development rights, so work that would normally need no application needs one here. Not every council has published its directions.
Archaeological priority area: City of Westminster APA 2.5
An assessment or field evaluation may be asked for before ground works.
The council or Historic England considers archaeology likely here. A desk-based assessment, and sometimes trial trenching, can be asked for with the application.
Air quality management area: Westminster AQMA
The council has declared the area as failing an air quality objective.
Schemes that add traffic, parking or combustion plant are assessed against the area's action plan and may need an air quality assessment.
Council record ↗
Central activities zone
The core of central London in the London Plan.
Offices, culture and the other strategic functions of the centre take priority over new housing here.
Also on the record
National infrastructure project 1606 m away: Thames Tideway Tunnel; Inside the City of Westminster built-up area; Public transport access: PTAL 6b (excellent), TfL 2023, for the 100 m square; Town centre 19 m away: West End; Priority habitat 31 m away: Deciduous woodland.
Not affected
Outside flood zones 2 and 3 · Not green belt · No scheduled monument at the site

Checked on 11 October 2026. Historic England, the Environment Agency, Natural England, the Planning Inspectorate, Transport for London (public transport access levels, Powered by TfL Open Data, OGL v3.0, contains OS data © Crown copyright and database right 2025) and council datasets, Open Government Licence. A boundary can run through a site and the council holds the definitive record: confirm with the council before relying on this.

Sales history 1

Last sold for £21,300,000 in January 2025. Other property, freehold.

24 January 2025£21,300,000Recorded as a transfer outside a standard sale

Sale prices from HM Land Registry's price paid record, matched to this application by its address.

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Important details

Application type
Full Planning Permission Application
Postcode
W1G 9DB
Received
30 Oct 2025
Validated
30 Oct 2025
Ward
Marylebone
Case officer
Show
Target decision
11 Mar 2026
Decision
Application Permitted
Decision date
11 Mar 2026
Decision level
Delegated Decision
Applicant
Show
Agent
DP9

How this decision compares

Decided in 132 days from validation, 58 days slower than Westminster's median of 74 for full applications. Approved, as 86% of full applications here are.

36%decided within 8 weeks
86%approved
2,057decided in the last year

Plota live figures for full applications decided by Westminster in the last twelve months, from validation. Westminster decision record →

Public comments

1comment received
1 neutral

56 neighbours consulted · Last counted 17 Oct 2026

Read the comments on the council site ↗

Consultation & key dates

Alt. reference
PP-14437290
Planning Portal ref
PP-14437290
Comments by
1 Dec 2025
Site or press notice
10 Nov 2025
Env. assessment
No
Westminster
Planning Authority Score
3.5/10
Below average
#221 of 296 councils
Relevant to this application:
Householder decisions

Westminster is slower than most councils at deciding householder applications, ranking #258 out of 296. Only 28% of applications have the time limit extended, well below the 41% national average - the council usually decides on time. Westminster is also one of the strictest councils - it refuses more householder applications than almost any other, with only 81% approved vs 90% nationally.

One of the strictest councils
only 81% approved vs 90% nationally
These figures are council-wide context, not a prediction for this application. View full council performance
Westminster decision statistics
Based on MHCLG data, the year to March 2026
86%
Overall approval rate
Below avg (87%) #201 of 296
81%
Householder approved
Below avg (90%) #277 of 296
44%
Decided in 8 weeks
Below avg (63%) #258 of 296
28%
Extended time limit
Below avg (41%) #46 of 296
83%
Minor dwellings approved
12 decided (1-9 homes)
67%
Major dwellings approved
3 decided (10+ homes)
81%
Change of use approved
133 decided
4,602
Total decisions
648 refused in the year to March 2026

Sale prices: Contains HM Land Registry data © Crown copyright and database right 2026. This data is licensed under the Open Government Licence v3.0.

Freehold boundary: © Crown copyright and database rights 2026, HM Land Registry. Polygons © Crown copyright and database rights 2026 Ordnance Survey 100026316. Conditions of use