Planning application
26/00802/FULL
11 Marylebone Mews London W1G 8PX
Proposal
Erection of a mansard roof extension, excavation and extension of the existing basement, installation of plant within a louvered acoustic enclosure on the rear flat roof at second floor and the replacement of the fenestration to the front and rear of the building; all to enlarge and alter dwellinghouse (Class C3).
As published by the council, reference 26/00802/FULL
Timeline
Dates from the published record
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10 Feb 2026
Received by Westminster
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21 Jul 2026
Added to PlanIndex
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Decision
Awaiting decision
The statutory target is eight weeks for most applications and thirteen for major development. Extensions of time are common.
What happens while it is decided
The process from here
This application is with Westminster for determination. The council publicises it, consults neighbours and technical bodies where required, and weighs the responses against local and national planning policy.
The statutory target is eight weeks for most applications and thirteen for major development, though extensions of time are common. Comments carry most weight while the case is undecided, so check the council portal for the deadline if you want to respond.
About full applications applications
How this application type works
A full application seeks permission for a complete, detailed proposal in one go: siting, design, access and landscaping are all fixed at this stage. It is the standard route for new buildings, conversions and changes of use. The statutory target is eight weeks for smaller schemes and thirteen weeks for major development, though complex cases often take longer by agreement.
Nearby applications
Within 500 metres
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26/01740/FULL Awaiting decision
64 Wimpole Street London W1G 8YS
Erection of a new roof terrace and green roof area at rear 2nd floor level; installation of plant and photovoltaic panels at main roof level and new mansard roof extension and installation of plant on the mews roof level; alterations at ground floor front elevation; Internal and external alterations throughout the building in connection with a rear elevation extension from first to fourth floor levels and the reconfiguration of the existing fifth floor level, installation of new double glazed windows throughout all in connection with a change of use to Class E (e) medical use.
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26/04440/LBC Awaiting decision
4 Marylebone Mews London W1G 8PY
Internal refurbishment of existing Studio Mews house including replacement of glazing to rooflights and minor external alterations. [Linked to 26/04439/FULL]
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26/04439/FULL Awaiting decision
4 Marylebone Mews London W1G 8PY
Internal refurbishment of existing Studio Mews house including replacement of glazing to rooflights and minor external alterations. [Linked to 26/04440/LBC]
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12/10824/ADFULL Granted
2 Marylebone Mews London W1G 8PU
Approval of details pursuant to Conditions 5 and 6 of planning permission dated 3 November 2011; namely for a sample of obscure glazing, detailed drawings of glass screen for windows and second floor terrace and detailed drawings of new windows and doors
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26/03230/LBC Awaiting decision
Hahnemann House 32 Welbeck Street London W1G 8EU
Alteration and improvement of existing heating and cooling to the Chapel through reinstatement of a working fan to dome, installation of fan coil units and an associated air source heat pump, removal of existing wall heating panels, and opening of fixed windows. (Linked to 26/03229/FULL)
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26/03229/FULL Awaiting decision
Hahnemann House 32 Welbeck Street London W1G 8EU
Alteration and improvement of existing heating and cooling to the Chapel through reinstatement of a working fan to dome, installation of fan coil units and an associated air source heat pump, removal of existing wall heating panels, and opening of fixed windows. (Linked to 26/03230/LBC)
Other full applications applications
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26/04824/ADFULL Granted
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26/04829/ADFULL Granted
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Details of external and internal signage strategy pursuant to Condition 33(E) of planning permission dated 8th April 2024 (RN: 23/00571/FULL)
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26/04841/ADFULL Granted
29 Henstridge Place London NW8 6QD
Details of the facing materials you will use, including glazing, and elevations and roof plans annotated to show where the materials are to be located pursuant to condition 5 of planning permission dated 18th November 2025 (RN:25/06159).
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26/04989/FULL Awaiting decision
1 Kildare Terrace London W2 5JT
Erection of a mansard roof extending over the main house and side wing, replacement lower ground rear extension with roof terrace above, lowering of lower ground floor slab, installation of an air source heat pump in rear garden, new front boundary treatment, and new second floor window on the north elevation.
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26/04986/FULL Awaiting decision
Inver Court Inverness Terrace London W2 6JB
Replacement of combustible materials in the render facades; timber decking and plastic soffits/ fascias to terraces with non-combustible materials on the 5th and 6th floors.