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Planning application

26/02817/FULL

17 Hertford Street London W1J 7RS

Awaiting decision Westminster Full Planning Permission Application

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 26/02818/LBC]

As published by the council, reference 26/02817/FULL

Timeline

Dates from the published record

  1. 28 Apr 2026

    Received by Westminster

  2. 21 Jul 2026

    Added to PlanIndex

  3. 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.

More on full applications applications in our guide

Nearby applications

Within 500 metres

  • 26/02818/LBC 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 26/02817/FULL]

    28 Apr 2026 0m away Heritage and listed buildings
  • 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)

    29 Oct 2025 2m away Full applications
  • 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)

    29 Oct 2025 2m away Heritage and listed buildings
  • 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)

    22 May 2026 2m away Full applications
  • 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)

    22 May 2026 2m away Heritage and listed buildings
  • 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.

    12 Feb 2007 5m away Heritage and listed buildings

In Westminster

  • 26/04824/ADFULL Granted

    New Zealand House 80 Haymarket London SW1Y 4TE

    Detailed design and specification of new blinds to NZH based on mock-up trials on-site. pursuant to condition 32 (i) of planning permission dated 8th April 2024 (23/00571/FULL).

    20 Jul 2026 Full applications
  • 26/04829/ADFULL Granted

    New Zealand House 80 Haymarket London SW1Y 4TE

    Details of external and internal signage strategy pursuant to Condition 33(E) of planning permission dated 8th April 2024 (RN: 23/00571/FULL)

    20 Jul 2026 Full applications
  • 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).

    20 Jul 2026 Full applications
  • 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.

    24 Jul 2026 Full applications
  • 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.

    24 Jul 2026 Full applications