Planning application
21 Montagu Mews South London W1H 7ES
Works: Extension Loft or dormer Roofing Windows or glazing
Still open. Anyone can comment while the consultation period runs, and comments go to the council rather than to us.
Proposal
Infill of existing light well to first floor at the rear, roof alterations including new conservation style roof lights and photovoltaic panels to the rear slope of the roof. Alterations to the front façade including the installation of new double doors with window over and removal metal bar to ground floor windows and installation of double glazed vacuum glazed double glazing within existing window units.
As published by the council, reference 25/09359/FULL
Application record
- Reference
- 25/09359/FULL
- Type
- Full Planning Permission Application
- Status
- Pending
- Received
- 24 Dec 2025
- Validated
- 26 Mar 2026
- Ward
- Marylebone
- Postcode
- W1H 7ES
Timeline
Dates from the published record
-
24 Dec 2025
Received by Westminster
-
26 Mar 2026
Validated
Checked as complete and ready for consideration.
-
20 Jul 2026
Added to PlanIndex
-
Decision
Awaiting decision
Decision expected by 21 May 2026, 8 weeks from validation under the statutory target for most applications. Extensions of time are common and are agreed case by case.
Westminster took a median of 66 days over the applications it decided in the last year.
Who's behind it
Company information only, from the register and Companies House
Robin Ashley Architects LLP Agent, an architecture practice registered in Sheffield
Active · incorporated 2004 · Sheffield
11 applications on PlanIndex · across 8 councils
Trade members see everything this firm has filed, how it was decided, and get an email the day it files again.
See their track recordDocuments
Plans, drawings, consultee responses and the officer's report
34 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.
Watch members (£5 a month) open the document list from here.
Open the documentsWhat happens while it is decided
This application is with Westminster for determination, against a statutory target of eight weeks. Over the last year Westminster decided full applications in a median of 91 days. More in our guide to how long planning decisions take.
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
-
3 Brunswick Mews London W1H 7FB
Details of appropriate arrangements to secure measures to mitigate the potential increased demand for on-street residents car parking in the vicinity of the site pursuant to condition 3 of planning permission dated 5th February 2025 (RN:24/08126/FULL)
Withdrawn Full applications 19 docs -
3 Brunswick Mews London W1H 7FB
Details of secure cycle storage for the residential (Class C3) use pursuant to condition 4 of planning permission dated 5th February 2025 (RN:24/08126/FULL)
Withdrawn Full applications 11 docs -
22 Montagu Mews South London W1H 7ES
Demolition of roof, part rear elevation, internal partitions and floors.
Granted Heritage and listed buildings Demolition 2 docs -
22 Montagu Mews South London W1H 7ES
Demolition of roof and replacement with extended roof and infill of rear lightwell.
Granted Full applications Extension Demolition 9 docs -
15 - 16 Montagu Mews South London W1H 7ET
Conversion of the existing ground-floor garage into habitable residential accommodation, replacement of existing windows and doors with double glazing, replacement of existing garage doors with new windows and installation of new rooflights.
Granted Full applications Loft or dormer Windows or glazing 25 docs -
11 Montagu Mews South London W1H 7ER
87% historically approved · decision due ~17 Jul
Installation of replacement existing windows with double glazed units to improve the thermal performance of the property.
Awaiting decision Full applications Windows or glazing 8 docs
Other full applications
In Westminster
-
26/06295/FULL Awaiting decision
15 Warwick Way London SW1V 1QT
Installation of a new shopfront with Medication Dispensing Outlet.
-
26/06297/FULL Awaiting decision
15 Warwick Way London SW1V 1QT
Alterations to rear elevation at basement level comprising replacement window and installation of double opening door.
-
26/06294/FULL Awaiting decision
15 Eaton Mews South London SW1W 9HP
Installation of railings and sliding lantern light at main roof level in connection with the use of the roof as a terrace.
-
26/06273/FULL Awaiting decision
9A Grosvenor Square London W1K 5AE
Installation of new natural Portland Stone step surfaces to the two highway facing front entrance doors. (Linked to 26/05473/LBC)
-
26/06277/FULL Awaiting decision
Hospital 60 Grove End Road London NW8 9NH
Variation of conditions 1 and removal of condition 6 of planning permission dated 12th November 2019 (RN 19/07202/FULL) for the Variation of condition 12 of planning permission dated 21 June 2013 (RN: 13/01330/FULL) for the: Demolition of single storey block to north east elevation of main hospital building. Erection of three storey building (plus basement level) with link to existing hospital fronting onto Grove End Road and erection of two storey extension to the main entrance building, both to provide additional hospital accommodation (Class D1). Installation of mechanical plant and associated external alterations. NAMELY, to include amended phase 2 drawings and condition 6 to be removed as the as approved 11 car parking space are no longer proposed and the car lift is no longer shown on the amended plans.