SW1X · Knightsbridge & Belgrave Square
SW1X is Knightsbridge and the grand northern half of Belgravia — Belgrave Square, Lowndes Square, Sloane Street and the Brompton Road frontage — running to the Kensington and Chelsea boundary on its western edge. Stucco terraces and later red-brick mansion blocks dominate, listed buildings are common, and retail and hotel uses hold the main roads. Flats have no permitted development rights, listed building consent reaches internal alterations, and applications succeed here on specification discipline and recent consented precedent rather than improvisation.
Location data: postcodes.io · Constraints: planning.data.gov.uk (borough-level) · Open Government Licence
Constraint context · Westminster
Real · planning.data.gov.ukWestminster has 56 designated conservation areas and 10 Article 4 areas. A district is too coarse to say which apply to your house — postcode districts span many streets and SW1X crosses 3 boroughs. Enter a full postcode below for the point-level check, or read the full borough picture on the Westminster planning guide.
Is SW1X in a conservation area?
Partly — and which part matters. A postcode district is never uniformly designated: SW1X contains 16 conservation areas within 1km of its centre, and whether your own property sits inside one decides whether permitted development survives. The centre point of SW1X itself falls inside Belgravia.
| Albert Gate | Nearby |
| Belgravia | At the centre |
| Birdcage Walk | Nearby |
| Brompton | Nearby |
| Chelsea | Nearby |
| Grosvenor Gardens | Nearby |
| Hans Town | Nearby |
| Knightsbridge | Nearby |
| Knightsbridge Green | Nearby |
| Mayfair | Nearby |
| Pimlico | Nearby |
| Queen’s Gate | Nearby |
| Royal Hospital | Nearby |
| Royal Parks | Nearby |
| Sloane Square | Nearby |
| Thurloe/Smith's Charity | Nearby |
Conservation areas whose official geometry lies within 1km of the centre of SW1X. Source: planning.data.gov.uk · Open Government Licence. Proximity to the district centre is not a statement about your own address — run the address check for that.
Does an Article 4 direction apply in SW1X?
Yes — SW1X has 10 Article 4 directions mapped within 1km of its centre. An Article 4 direction withdraws specific permitted-development rights on the streets it covers, which is the most common reason a project that looks like permitted development turns out to need a full application. The centre point of SW1X falls inside Article 4 Basement Development Permitted Rights Removed.
| 1, 4, 8, 11, 12, 13 Relton Mews, SW7 | Nearby |
| 6-10 Moncorvo Close, SW7 | Nearby |
| Article 4 - No 100 | Nearby |
| Article 4 - No 106 | Nearby |
| Article 4 - No 60 | Nearby |
| Article 4 - No 71 | Nearby |
| Article 4 - No 72 | Nearby |
| Article 4 Basement Development Permitted Rights Removed | At the centre |
| Article 4 Direction Class E To C3 In Central Activities Zone | Nearby |
| Article 4 Direction Class E To C3 Out Central Activity Zone | Nearby |
Article 4 directions whose official geometry lies within 1km of the centre of SW1X. Source: planning.data.gov.uk · Open Government Licence. The national dataset omits some property-specific directions — the council register is always definitive.
Every designation in the borough: Westminster planning guide →
Do you need planning permission in SW1X?
Three routes exist, and which one you are on is decided by your address, not your postcode district:
| Permitted development — no application. The work stays inside the GPDO limits and no designation removes them. A Lawful Development Certificate is cheap proof for a future buyer. | No permission |
| Prior approval — the larger single-storey rear extension route, with neighbour consultation. Not available on designated land. | 42 days |
| Full householder application — required once a designation removes your permitted-development right, or the scheme exceeds the limits. | 8 weeks |
SW1X contains mapped conservation-area or Article 4 geometry, so a meaningful share of its streets will have lost some permitted-development rights — which pushes those properties onto the full-application route. Whether yours is one of them is an address-level question, not a district-level one.
What does planning permission cost in SW1X?
| Householder planning application | £548 (from 1 April 2026) |
| Lawful Development Certificate — proposed works | £274 (half the application fee) |
| Lawful Development Certificate — existing works | £548 (the full application fee) |
| Listed building consent | No fee |
| Resubmission after a refusal | Free once, within 12 months of the decision |
National statutory figures for England — councils do not set them, so they are the same in every borough. Planning fees re-index every 1 April; confirm the current amount on the Planning Portal fee calculator before you apply. These are the council's fees only — drawings, surveys and any specialist reports are separate.
How long does it take?
| Householder application — statutory target | 8 weeks |
| Householder application — in practice | 8–12 weeks |
| Prior approval (larger home extension) | 42 days |
| Lawful Development Certificate | 8 weeks |
| Householder appeal — deadline to lodge | 12 weeks from the decision date |
| Householder appeal — typical decision | Around 18 weeks |
What if it's refused?
A refusal is a decision notice with reasons attached, and those reasons are a roadmap. Most homeowners in Westminster — as anywhere in England — are better served by amending the scheme and using the free resubmission than by appealing: you get one further application on the same site within 12 months without paying again.
| Who can appeal | The applicant only — not neighbours |
| Fee to appeal | None — you bear your own costs |
| Procedure | Written representations for most householder appeals |
| Success rate | Roughly a third — about 36% of householder appeals allowed in 2025/26 |
Appeals go to the Planning Inspectorate, an independent national body. How to read a refusal and choose your route →
Planning permission by project in Westminster
Mostly flats and listed stock — assume a full application and check for listed building consent.
Rear extension in Westminster →Rare — the terrace typologies and flat conversions of Westminster offer few side returns.
Side return extension in Westminster →Roof-level changes face the strictest control in London — precedent and heritage statements essential.
Loft conversion in Westminster →Tightly limited and excluded under most listed buildings; expect maximum scrutiny.
Basement extension in Westminster →Limited garden stock; where gardens exist, conservation-area rear placement still qualifies for PD.
Garden room in Westminster →Pinpoint your street
More of Westminster
The most heritage-constrained borough in the country.
Borough page →Planning Permission Checker provides planning and cost intelligence for early feasibility only. It is not legal, planning, valuation, architectural, structural, or surveying advice. All estimates are indicative and must be verified by qualified professionals before purchase, design, planning submission, or construction.
Cost estimates are indicative only — not a quotation. Final price depends on survey, specification, structure, access, party wall matters, VAT, professional fees, and contractor availability.
Planning outcomes are not guaranteed. Local planning authorities make final decisions.