17 William Mews London SW1X 9HF Data via plota.co.uk
Proposal
Amendments to planning permission dated 12 June 2025 (RN: ) for the erection of a roof extension and alterations to existing front elevation and fenestration. Excavation of a new basement below part existing dwellinghouse.; NAMELY amendments to ground floor front elevation including amendments to the approved window openings, together with associated internal reconfiguration works. Data via plota.co.uk
Application progress
Refused on 9 Jun 2026 · Delegated Decision · Last checked 20 Jul 2026
Documents 14
Decision & officer reports 2
Statements & assessments 1
Plans & drawings 4
Application forms 1
Other documents 6
Associated applications 5
- AmendmentAmendments to planning permission dated 12 June 2025 (RN) for the erection of a roof extension…RefusedThis application26/02952/NMA
Show 3 more · 2 approved, 1 refused
Site constraints 9
Show all 20 with distances
- 29 m11 and 12, Lowndes Square Sw1Grade II
- 58 m1-15, Wilton Crescent Sw1Grade II
- 79 m9-12 and 14-28, Wilton Place Sw1Grade II
- 107 mThe Turks Head Public HouseGrade II
- 113 m11-18, MOTCOMB STREET SW1 (See details for further address information)Grade II
- 116 m34-50, Wilton Crescent Sw1Grade II
- 117 mWilton ArmsGrade II
- 122 m5-12, William Street W1Grade II
- 132 mPantechniconGrade II
- 133 m29-31, Wilton Place Sw1Grade II
- 133 m16-30, Wilton Crescent Sw1Grade II
- 134 m1-3, Wilton Terrace Sw1Grade II
- 135 m1-8, Motcomb Street Sw1Grade II
- 136 m190-192 Sloane StreetGrade II
- 140 m1-8, Wilton Place Sw1Grade II
- 143 mNumbers 20-23 and 23a Motcomb Street and Number 15 Lowndes StreetGrade II
- 144 mChurch of St PaulGrade II*
- 145 m11a, Belgrave Square Sw1Grade II
- 147 mK6 Telephone Kiosk Outside Number 28Grade II
- 147 m2-12 Halkin Arcade and 27 and 28 Motcomb Street and 11a West Halkin StreetGrade II
Checked on 6 October 2026. Historic England, the Environment Agency, Natural England, the Planning Inspectorate, Transport for London (public transport access levels, Powered by TfL Open Data, OGL v3.0, contains OS data © Crown copyright and database right 2025) 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.
Sales history 1
Last sold for £2,530,000 in May 2021. Other property, freehold.
Sale prices from HM Land Registry's price paid record, matched to this application by its address.
Building
From the energy performance certificate lodged in February 2021, the latest held for this property. The building may have changed since. View the certificate
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Important details
- Council
- Westminster
- Application type
- Non-material amendments
- Postcode
- SW1X 9HF
- Received
- 5 May 2026
- Validated
- 12 May 2026
- Ward
- Knightsbridge & Belgravia
- Case officer
- Show
- Target decision
- 9 Jun 2026
- Decision
- Application Refused
- Decision date
- 9 Jun 2026
- Decision level
- Delegated Decision
- Applicant
- Show
- Agent
- Savills
- Freehold owner
- Show
How this decision compares
Decided in 28 days from validation, 27 days faster than Westminster's median of 55 for extensions. Refused, as 12% of extensions here are.
Plota live figures for extensions decided by Westminster in the last twelve months, from validation. Westminster decision record →
Consultation & key dates
- Alt. reference
- PP-14900570
- Planning Portal ref
- PP-14900570
- Env. assessment
- No
Historical activity at this location
26 previous applications on record - archival context, not part of the live application.
Previous applications at this address
Nearby activity
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.
Sale prices: Contains HM Land Registry data © Crown copyright and database right 2026. This data is licensed under the Open Government Licence v3.0.
Freehold boundary: © Crown copyright and database rights 2026, HM Land Registry. Polygons © Crown copyright and database rights 2026 Ordnance Survey 100026316. Conditions of use
Energy performance: Energy performance certificates from the Energy Performance of Buildings Register, Ministry of Housing, Communities and Local Government. Contains public sector information licensed under the Open Government Licence v3.0. © Crown copyright 2026.
Freehold owner: Information produced by HM Land Registry. © Crown copyright 2026. Source: HM Land Registry, UK and overseas companies that own property in England and Wales, September 2026 release.
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17 William Mews London SW1X 9HF
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Freehold owner, on paid plans
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Council archive
17 William Mews London SW1X 9HF
Erection of additional storey and roof terrace to existing single family dwelling house, alterations to existing front elevation and fenestration and creation of basement below part existing dwelling
- Received
- 28 Oct 2024
- Outcome
- Pending