Planning application
26/02818/LBC
17 Hertford Street London W1J 7RS
Proposal
Replacement of non-original casement windows at Level 03 with timber sash windows; new structure for mansard extension, infill of existing lightwell and repositioning of skylight above stairwell. [Linked to 26/02817/FULL]
As published by the council, reference 26/02818/LBC
Timeline
Dates from the published record
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28 Apr 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 heritage and listed buildings applications
How this application type works
Heritage applications concern listed buildings and conservation areas. Listed building consent is needed for works, inside or out, that affect the special interest of a listed building, and carrying out such works without consent is a criminal offence. The council weighs harm to the heritage asset against any public benefit of the proposal.
More on heritage and listed buildings applications in our guide
Nearby applications
Within 500 metres
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26/02817/FULL Awaiting decision
17 Hertford Street London W1J 7RS
Replacement of non-original casement windows at Level 03 with timber sash windows; new structure for mansard extension, infill of existing lightwell and repositioning of skylight above stairwell. [Linked to 26/02818/LBC]
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25/07827/FULL Awaiting decision
17 Hertford Street London W1J 7RS
Internal restoration, redecoration and minor reconfigurations associated with the implementation of planning permission (24-03931-FULL) and listed building permission (24-03932-LBC); addition of a fourth-floor mansard roof to allow for the creation of a one-bedroom apartment for short term letting purposes; replacement of existing windows at third floor level with traditional timber sashes and other associated works. (Linked 25/07828/LBC)
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25/07828/LBC Awaiting decision
17 Hertford Street London W1J 7RS
Addition of a fourth-floor mansard roof to allow for the creation of a one-bedroom apartment for short term letting purposes, replacement of windows at third floor level, internal and external restoration, redecoration and minor reconfigurations and other associated works. (Linked with 25/07827/FULL)
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26/03409/FULL Awaiting decision
17 Hertford Street London W1J 7RS
Replacement of the mansard infill extension to the south east of the property by extending the existing bay upwards by a single storey (3-storeys total) and associated roof works to improve the internal space. (Linked with 26/03410/LBC)
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26/03410/LBC Awaiting decision
17 Hertford Street London W1J 7RS
Replacement of the mansard infill extension to the south east of the property by extending the existing bay upwards by a single storey (3-storeys total) and associated roof works to improve the internal space. (Linked with 26/03409/FULL)
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07/01340/LBC Granted
17 Hertford Street London W1J 7RS
Installation of nine air-conditioning units at roof level and replacement of roof access enclosure and rooflight; installation of associated internal units and pipework.
Other heritage and listed buildings applications
In Westminster
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26/04984/LBC Awaiting decision
47G Randolph Avenue London W9 1BQ
Installation of replacement fire surround.
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26/04997/LBC Awaiting decision
Hanover Lodge Outer Circle Regent's Park London NW1 4HB
Erection of a morning room side extension. (Linked to 26/04996/FULL)
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26/04979/LBC Awaiting decision
12 Brewer Street London W1F 0SF
Internal alterations including removal of internal enclosures; Replacement flooring, shelving and slatwall systems, staircase handrail repair and other associated joinery works.
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26/04987/LBC Awaiting decision
Basement And Ground Floor 8 Ganton Street London W1F 7QL
Repainting of the existing timber shopfront, hand-painted fascia lettering, installation of a new hanging sign using the existing projecting sign bracket, and installation of a discreet fascia-mounted LED trough light.
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26/04995/LBC Awaiting decision
Hanover Lodge Outer Circle Regent's Park London NW1 4HB
Erection of rear conservatory extensions and an entrance loggia to side with roof terrace above, together with associated landscaping and alterations. (Linked with 26/04994/FULL)