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17 Hertford Street London W1J 7RS

26/03410/LBCHeritageApproved
Listed building consent

Approved on 27 August 2026

Site boundary (council red line)

Proposal

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)

Received
22 May 2026
  1. Received22 May
  2. Validated11 Jun
  3. Consult.
  4. Target
  5. Decided27 Aug

Decided in 77 days (council typically 49)

About this application

This is a heritage application for an extension at 17 Hertford Street London W1J 7RS. Westminster has handled 2,677 applications of this type. This one was decided in 77 days, 4 weeks longer than Westminster's typical decision time. The site is in the Mayfair conservation area, with 17 listed buildings nearby. There have been 8 other applications at this address. In the past year there have been 484 applications across West End. We hold 940 applications in total for the W1J postcode area.

93% of heritage applications at City of Westminster were approved. Across all application types, the council typically decides in about 7 weeks (median).

Based on decided applications received in the last 3 years.See what's approved near your address

Application details

Postcode
W1J 7RS
Application type
Heritage
Scale / size
Small

Planning application dates

Date validated
11 June 2026
Consultation expiry
15 July 2026

Applicant and agent

Architect profile
ARYA DOUGE LTD

Site constraints

Checking the site
2/3
Council recordsAppealsFlood risk

Designations that overlap or adjoin the site outline.

  • Conservation area: Mayfair
  • Listed building: Grade II: 17, Hertford Street W1On this site · +3 more
  • Article 4 direction: Article 4 Basement Development Permitted Rights Removed
  • Flood zone 1: Low probability (rivers and sea)
Also checked, none recorded (21)

flood storage areas, tree preservation orders, green belt, scheduled monuments, World Heritage Sites, World Heritage Site buffer zones, registered parks and gardens, registered battlefields, Heritage at Risk entries, nutrient neutrality catchments, national parks, National Landscapes, SSSIs, Special Areas of Conservation, Special Protection Areas, Ramsar sites, ancient woodland, national nature reserves, local nature reserves, heritage coasts and brownfield registers.

A guide only, from official open data; it is not a planning search. Flood zones cover rivers and sea, not surface water.

Data © Crown copyright and others · sources and licences

Contains public sector information from planning.data.gov.uk (MHCLG and local planning authorities), licensed under the Open Government Licence v3.0. © Crown copyright and database right 2026.

© Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026. The Historic England GIS Data contained in this material was obtained on 2026-11-03. The most publicly available up to date Historic England GIS Data can be obtained from HistoricEngland.org.uk.

© Natural England copyright. Contains Ordnance Survey data © Crown copyright and database right 2026.

© Environment Agency copyright and/or database right 2026. All rights reserved. Flood Map for Planning, Open Government Licence v3.0.

Contains Ordnance Survey data © Crown copyright and database right 2026.

Source: Office for National Statistics licensed under the Open Government Licence v.3.0. Contains OS data © Crown copyright and database right 2026.

Associated applications

  1. 2026
    11 Jun

    Replacement of the mansard infill extension to the south east of the property by extending the existing bay…

    ApprovedFullPart of26/03409/FULL
  2. 2026
    11 Jun

    Replacement of the mansard infill extension to the south east of the property by extending the existing bay…

    This applicationApprovedListed building consent26/03410/LBC

Planning history at this site

7 other applications at this property, newest first.

  1. 2026
    9 Sep

    Internal alterations to the basement including new lightweight timber-stud partitions to reorganise the…

    ApprovedListed building consent26/06165/LBC
  2. 2026
    22 May

    Details of all new windows / reduction in size of dormer windows / facing materials pursuant to conditions 4…

    ApprovedListed building consent26/03484/ADLBC
  3. 2026
    22 May

    Details of all new windows / reduction in size of dormer windows / facing materials pursuant to conditions 4…

    ApprovedDischarge of conditions26/03406/ADFULL
  4. 2026
    28 Apr

    Replacement of non-original casement windows at Level 03 with timber sash windows; new structure for mansard…

    WithdrawnFull Planning Permission Application26/02817/FULL
  5. 2026
    28 Apr

    Replacement of non-original casement windows at Level 03 with timber sash windows; new structure for mansard…

    WithdrawnListed building consent26/02818/LBC
  6. 2025
    6 Nov

    Internal reconfigurations, restoration and associated works.

    ApprovedListed building consent25/07828/LBC

Source: Westminster

Contains public sector information from the Planning London Datahub, licensed under the Open Government Licence v3.0.

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