39 Westminster Mansions Great Smith Street London SW1P 3BP Data via plota.co.uk

26/04402/FULL - Full Planning Permission Application Approved
Extensions & alterations

Proposal

Retention of slimline double-glazed units featuring internal glazing bars to five existing double-hung timber sash windows on the front elevation. Data via plota.co.uk

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View original council record ↗Last checked

Application progress

✓
Received
3 Jul 2026
✓
Validated
20 Jul 2026
✓
Approved
27 Aug 2026

Approved on 27 Aug 2026 · Delegated Decision · Last checked 28 Aug 2026

Documents 19

Decision & officer reports 2

PDF GRANT OF FULL PP [PE] Decision Notice · 27 Aug 2026 View ↗ PDF DELEGATED REPORT Report · 27 Aug 2026 View ↗

Statements & assessments 3

PDF REV A PLANNING STATEMENT Planning Statement · 3 Aug 2026 View ↗ PDF SUSTAINABLE DESIGN STATEMENT Sustainability appraisal · 3 Aug 2026 View ↗ PDF SUPERSEDED - PLANNING HERITAGE STATEMENT Superseded document · 3 Jul 2026 View ↗

Plans & drawings 5

PDF LOCATION PLAN Location Plan · 20 Jul 2026 View ↗ PDF PROPOSED SASH WINDOW (AS BUILDS) TYPICAL DETAIL DRAWINGS Drawing · 20 Jul 2026 View ↗ PDF EXISTING SASH WINDOW (BEFORE WORKS) TYPICAL DETAIL DRAWINGS Drawing · 20 Jul 2026 View ↗ PDF EXISTING AND PROPOSED (BEFORE WORKS AND AS BUILD) WINDOW ELEVATIONS Drawing · 20 Jul 2026 View ↗ PDF EXISTING AND PROPOSED ELEVATIONS Drawing · 20 Jul 2026 View ↗

Application forms 1

PDF APPLICATIONFORMREDACTED Application Form · 3 Jul 2026 View ↗

Consultation & comments 1

PDF NEIGHBOUR NOTIFICATION LETTER (21D) Background Papers · 24 Jul 2026 View ↗

Other documents 7

PDF SITE NOTICE 21 OR 28 DAYS IF T&C APPL. Background Papers · 24 Jul 2026 View ↗ PDF CNSLT-LA SOCIETY Background Papers · 24 Jul 2026 View ↗ PDF CNSLT-LA SOCIETY Background Papers · 24 Jul 2026 View ↗ PDF ACK-GENERAL LETTER (G/P/C) Background Papers · 24 Jul 2026 View ↗ PDF 2ND INVALID LETTER Background Papers · 16 Jul 2026 View ↗ PDF RECEIPT OF APPLICATION Other · 6 Jul 2026 View ↗ PDF 1ST INVALID LETTER Background Papers · 6 Jul 2026 View ↗

All documents on the council site ↗

Site constraints 10

Flood zone 3, rivers and sea
High chance: a 1 in 100 or greater annual chance from rivers, or 1 in 200 from the sea. Any development here needs a flood risk assessment. Defences are not counted.
The Environment Agency flood map for planning. Homes in zone 3 must also pass the sequential test. Surface water flooding is a separate map.
Flood map ↗
Westminster Abbey And Parliament Square conservation area
Demolition needs planning permission and permitted development is restricted.
The council must give weight to preserving or enhancing the area's character and appearance. Not every council has published its boundaries as open data.
Council document ↗
Article 4 direction
Article 4 Basement Development Permitted Rights Removed. Named permitted development rights are withdrawn here.
An Article 4 direction withdraws particular permitted development rights, so work that would normally need no application needs one here. Not every council has published its directions.
Archaeological priority area: City of Westminster APA 1.1
An assessment or field evaluation may be asked for before ground works.
The council or Historic England considers archaeology likely here. A desk-based assessment, and sometimes trial trenching, can be asked for with the application.
Air quality management area: Westminster AQMA
The council has declared the area as failing an air quality objective.
Schemes that add traffic, parking or combustion plant are assessed against the area's action plan and may need an air quality assessment.
Council record ↗
Central activities zone
The core of central London in the London Plan.
Offices, culture and the other strategic functions of the centre take priority over new housing here.
78 listed buildings within 150 m
Nearest: Mary Sumner House, Grade II, 39 m away · 4 Grade I, 22 Grade II*, 52 Grade II
The site itself is not listed. Listed building consent is needed for work that affects the special interest of a listed building, inside or out, on top of planning permission. Setting can be a consideration for buildings nearby; there is no fixed radius.
Show all 78 with distances
Historic England ↗
World heritage site 96 m away: Palace of Westminster, Westminster Abbey and St. Margaret's Church
Its setting is a consideration for work nearby.
Registered parks and gardens, battlefields, world heritage sites and protected wrecks are designated heritage assets: harm needs clear and convincing justification.
Historic England ↗
Also on the record
Scheduled monument 202 m away: The Jewel Tower; Inside the City of Westminster built-up area.
Not affected
Not green belt

Checked on 11 September 2026. Historic England, the Environment Agency, Natural England and council datasets, Open Government Licence. A boundary can run through a site and the council holds the definitive record: confirm with the council before relying on this.

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Important details

Council
Westminster
Application type
Full Planning Permission Application
Postcode
SW1P 3BP
Received
3 Jul 2026
Validated
20 Jul 2026
Ward
St James's
Case officer
Show
Target decision
14 Sept 2026
Decision
Application Permitted
Decision date
27 Aug 2026
Decision level
Delegated Decision
Applicant
Show
Agent
Show

How this decision compares

Decided in 38 days from validation, 15 days faster than Westminster's median of 53 for extensions. Approved, as 87% of extensions here are.

62%decided within 8 weeks
87%approved
930decided in the last year

Plota live figures for extensions decided by Westminster in the last twelve months, from validation. Westminster decision record →

Public comments

No public comments yet.

56 neighbours consulted · Last counted 28 Aug 2026

Read the comments on the council site ↗

Consultation & key dates

Alt. reference
PP-15008059
Site or press notice
5 Aug 2026
Env. assessment
No

Historical activity at this location

25 nearby applications on record - archival context, not part of the live application.

Within ~100m

Nearby activity

2025
Church House Conference Centre Dean's Yard London SW1P 3NZ
Installation of air handling unit at roof level, and associated enabling works and replac…
25/06523/LBC
2025
Church House Conference Centre Dean's Yard London SW1P 3NZ
Installation of air handling unit at roof level, and associated enabling works and replac…
25/06522/FULL
2025 Withdrawn
Emmanuel Evangelical Church 9 - 23 Marsham Street London SW1P 3DW
T1: Cherry Laurel: Remove to ground level and grind resulting stump.
25/04001/TCA
2025
9 Gayfere Street London SW1P 3HN
A new roof structure to roof level and upgrading of roof lights on level 3 roof.
25/02651/FULL
2025 Approved
19 Cowley Street London SW1P 3LZ
T1. London plane: crown reduce to previous, most recent reduction points, retaining good…
25/01958/TPO
2024
3 Cowley Street London SW1P 3NB
T1 Lime ? Reduce back to previous points of reduction by removing approx. 1.5m worth of r…
24/06719/TCA
2024
Church House Great Smith Street London SW1P 3BL
Internal works comprising of the refurbishment of a teapoint in the area of the historic…
24/06621/LBC
2024 Approved
Edward Alsop Court 18 Great Peter Street London SW1P 2BT
T1 Silver birch: fell
24/03719/TCA
2024 Approved
8 Gayfere Street London SW1P 3HN
Replacement of window with new door opening, replacement rooflight and installation of ra…
24/02432/FULL
2024 Approved
24 Tufton Street London SW1P 3RB
Confirmation that the proposed installation of four new steel windows to the rear elevati…
24/00293/CLOPUD
2024
Emmanuel Evangelical Church 9 - 23 Marsham Street London SW1P 3DW
Replacement of damaged internal floors tile with like-for-like tiles.
24/03621/LBC
2023
40 Great Smith Street London SW1P 3BU
Excavation of single storey basement associated internal alterations to main building; de…
23/08397/FULL
2023
40 Great Smith Street London SW1P 3BU
Excavation of single storey basement associated internal alterations to main building; de…
23/08398/LBC
2022 Withdrawn
31 Great Peter Street London SW1P 3LR
Construction of a two storey roof extension incorporating a roof terrace above; new slate…
22/05060/FULL
2023
24 Westminster Mansions Great Smith Street London SW1P 3BP
Replacement of windows with double glazed slimline heritage sash windows at lower ground…
23/03113/FULL
2022 Approved
29 Great Peter Street London SW1P 3LW
Installation of emergency smoke extract duct and emergency generator exhaust flue with at…
22/01194/FULL
2022 Approved
29 Great Peter Street London SW1P 3LW
Installation of five condenser units and acoustic enclosure, acoustic canopy and acoustic…
22/03260/FULL
2022 Approved
Flat 35 Tufton Court 41-51 Tufton Street London SW1P 3QH
Replacement of windows with double-glazed oak sash windows.
22/05877/FULL
2022 Approved
34 Westminster Mansions Great Smith Street London SW1P 3BP
Replacement of single glazed windows with double glazed windows to match existing.
22/06702/FULL
2022 Withdrawn
40 Great Smith Street London SW1P 3BU
Excavation of single storey basement; demolition of rear office extension and erection of…
22/02493/FULL
2016 Approved
24 Tufton Street London SW1P 3QZ
Installation of replacement floor and associated internal alterations.
16/09368/LBC
2016 Approved
16 Cowley Street London SW1P 3LZ
Installation of one blue ceramic commemorative plaque at ground floor level.
16/09262/LBC
2016 Refused
Hope House 45 Great Peter Street London SW1P 3LT
The erection of a roof terrace with glazed balustrade at seventh floor level together wit…
16/08257/FULL
2016 Refused
18 Cowley Street London SW1P 3LZ
Masonry cleaning of brickwork and associated repairs to facade..
16/05625/LBC
2016 Withdrawn
18 Cowley Street London SW1P 3LZ
Cleaning and repairs to brickwork on Cowley and St Peters Street frontages.
16/04733/LBC
Westminster
Planning Authority Score
3.5/10
Below average
#221 of 296 councils
Relevant to this application:
Householder decisions

Westminster is slower than most councils at deciding householder applications, ranking #258 out of 296. Only 28% of applications have the time limit extended, well below the 41% national average - the council usually decides on time. Westminster is also one of the strictest councils - it refuses more householder applications than almost any other, with only 81% approved vs 90% nationally.

One of the strictest councils
only 81% approved vs 90% nationally
These figures are council-wide context, not a prediction for this application. View full council performance
Westminster decision statistics
Based on MHCLG data, the year to March 2026
86%
Overall approval rate
Below avg (87%) #201 of 296
81%
Householder approved
Below avg (90%) #277 of 296
44%
Decided in 8 weeks
Below avg (63%) #258 of 296
28%
Extended time limit
Below avg (41%) #46 of 296
83%
Minor dwellings approved
12 decided (1-9 homes)
67%
Major dwellings approved
3 decided (10+ homes)
81%
Change of use approved
133 decided
4,602
Total decisions
648 refused in the year to March 2026
Source: MHCLG planning statistics · See full council rankings