Basement
conversions
in Lancaster Gate, W2
Architects, Engineers, Surveyors & Builders Under One Roof.
Hampstead Chartered Surveyors & Building ConsultancyOne Studio. One Contract. One Team.
Lancaster Gate's terraces were built as a monumental group framing the spire of the former Christ Church, Westminster's Bayswater guide notes, and several are listed Grade II. A basement project here works within that listing.
Lancaster Gate sits in the City of Westminster within the Bayswater Conservation Area, on the grand stuccoed terraces that face Kensington Gardens directly. Westminster scrutinises external change closely here, and because the park-facing stucco is protected as a group, a basement beneath one of these mansion-flat conversions has to answer to the terrace as a whole, not just the flat above it.
Lancaster Gate itself is a monumental set of white-fronted terraces around its own gardens, while Craven Terrace and Leinster Terrace add handsome period houses and conversions nearby — stock now largely split into leasehold mansion flats, which layers freeholder consent and party-wall agreements on top of Westminster's basement scrutiny. Flat refurbishment costs here are already driven by freeholder approvals, mansion-flat acoustics, concealed service routes, facade and sash repair and central-W2 access logistics, and a basement or roof interface adds directly onto that list.
Once consent and party-wall matters are settled, the numbers follow a familiar split: converting existing cellar space under a Lancaster Gate flat is priced differently from a new excavation with underpinning, fit-out excluded.
Lower floors under Lancaster Gate's listed terraces
Westminster's Bayswater guide describes the monumental Lancaster Gate development framing the spire of the former Christ Church, whose tower and spire are listed Grade II. The terraces themselves include listed groups such as Nos 1 to 9, Nos 10 to 22 and Nos 75 to 89 Lancaster Gate, all Grade II.
For a listed house, Westminster's City Plan asks that basement work protects the heritage asset and does not unbalance the building's original hierarchy of spaces where that hierarchy contributes to its significance. The lower floor stays the service floor it was built as, improved rather than reinvented.
New excavation anywhere in the city has needed planning permission since Westminster's Article 4 direction of July 2016, and the plan treats a single storey of about 2.7m below the original lowest floor as the appropriate maximum.
Every basement development must come with a structural methodology statement, which also covers flood risk, the plan says. In terraces of this scale, the engineer's survey of the party walls and the existing vaults comes first.
Westminster's guide also lists the garden in front of several Lancaster Gate terraces among the spaces protected by the London Squares Act 1931. Basement works stay inside the house's own boundary, and the square is never used for storage or access.
Westminster's guide counts approximately 1,800 listed buildings across the Bayswater conservation area, which takes in Lancaster Gate. A lower-floor project under one of these terraces therefore begins with the list entry, the plan of the original service floor and the condition of the existing walls.
Not in Lancaster Gate, but a related project: Belsize Park Gardens, NW3, a whole-house refurbishment in Belsize Park that took in basement, extension and loft works.
Most Lancaster Gate houses are now divided into flats, so basement work is agreed with the freeholder and the other leaseholders before any design is fixed.
Sources: Westminster City Council: Bayswater conservation area mini guide (October 2004); Historic England: tower and spire of Christ Church, Lancaster Gate, list entry 1275008, Grade II; Historic England: Nos 1 to 9 Lancaster Gate, list entry 1221691, Grade II; Historic England: Nos 10 to 22 Lancaster Gate, list entry 1221694, Grade II; Historic England: Nos 75 to 89 Lancaster Gate, list entry 1275011, Grade II; Westminster City Plan 2019-2040 (2026), adopted 21 January 2026; Westminster City Council: Article 4 directions in Westminster.
Basement Conversions in Lancaster Gate: Questions
Can a Lancaster Gate basement flat be extended downwards?
Only with planning permission, under Westminster's city-wide basement Article 4 direction, and with listed building consent where the terrace is listed, as Nos 1 to 9 Lancaster Gate are. The freeholder's consent is needed too where the lease requires it.
Does the Bayswater Conservation Area cover basement work in Lancaster Gate?
Yes: Lancaster Gate sits in the City of Westminster within the Bayswater Conservation Area, on the grand stuccoed terraces facing Kensington Gardens, and Westminster protects that park-facing stucco as a group — so a basement scheme is judged against the whole terrace.
Who needs to consent to a basement beneath a Lancaster Gate mansion flat?
Both the freeholder and Westminster: the mansion blocks add freeholder and party-wall layers on top of the borough's scrutiny, and flat refurbishment costs here are already shaped by freeholder approvals and concealed service routes before a basement is even added.
Which Lancaster Gate streets face Kensington Gardens, and does that affect a basement conversion?
Lancaster Gate itself is a monumental set of white-fronted terraces around its gardens, with Craven Terrace and Leinster Terrace nearby facing the park — group-protected stucco that means a basement is treated as part of the terrace rather than a single flat.
What else adds to a Lancaster Gate basement budget beyond the dig itself?
Freeholder approvals, mansion-flat acoustics, concealed service routes, facade and sash repair, roof or basement interfaces and central-W2 access logistics all sit alongside the excavation cost on a Lancaster Gate scheme.
Cellar conversion or new excavation — what's the cost difference for a Lancaster Gate basement?
Converting existing cellar space under a Lancaster Gate flat and digging a new excavation with underpinning are priced differently, and each is quoted after a survey; fit-out is priced separately.
Book a feasibility visit
Request a visit
Completed renovation project examples
