Mansion flat renovation
and refurbishment
in Knightsbridge, SW1X / SW7

The Hans Town statement names No. 61 Cadogan Square, built in 1879, as the earliest high-class apartment building erected in London. Henry Holland named his development Hans Town after Sir Hans Sloane, whose daughter-heiress married into the Cadogan family.

A flat brings different planning rules from a house. RBKC's Local Plan 2024 notes that dwellinghouses have permitted development rights but buildings such as mansion blocks, often in multiple ownership, do not, and that flats may need planning permission for new windows if the building's appearance will be materially altered.

For cooling, RBKC's Local Plan asks anyone proposing air conditioning, even a single unit, to consider its environmental impact and fully explore passive cooling and ventilation first, and Policy GB8 resists plant, heat pumps included, with an unacceptable noise and vibration impact on surrounding amenity. In a listed building, air conditioning is also on RBKC's list of works needing consent.

On the Westminster side, the mini guide describes the central part of its conservation area, developed in the mid-19th century, as large stucco houses detailed in a classical manner, including Princes Gate, Rutland Gate, Queens Gate and part of Ennismore Gardens.

Sources: Royal Borough of Kensington and Chelsea: Hans Town Conservation Area Proposals Statement (adopted January 2000), Royal Borough of Kensington and Chelsea: Local Plan (adopted July 2024), Royal Borough of Kensington and Chelsea: listed buildings explained, Westminster City Council: Knightsbridge conservation area mini guide

North of Brompton Road the council is Westminster, and its 2009 audit explains how the area's flats came about. By the late Victorian period many of the grand terraced family houses were thought too large, and new building took the form of mansion flat blocks instead.

Blocks of flats came back in the 1930s, after the First World War, and went on being built until the 1960s, when the last residential buildings in the area went up. Facing the park, only one complete original terrace survives, 14-31 Princes Gate; the rest gave way to modern apartment blocks.

Of the big terraced houses that remain, a good number are now flats and others belong to embassies or institutions, so a flat may share its building with a mission or an institute as well as with other homes.

Almost all the open space here is private communal garden, the audit notes, and the seven garden squares are of central importance to the area's character. Works are planned so that nothing is stored in, or delivered across, a communal garden.

In a converted house we confirm early which walls and floors belong to the flat and which to the building, because embassies and institutions next door often have their own security and access rules that the programme must respect.

Blocks of the 1930s to 1960s may have concrete floors and shared risers; we survey the risers and the floor build-up first, because they decide where a new kitchen or bathroom can sit and how much sound insulation a hard floor needs.

A flat in a late Victorian mansion block may keep its original doors, architraves and fireplaces, which we list at the survey and protect throughout, since modern replacements rarely match their timber and mouldings.

Source: Westminster City Council: Knightsbridge, Knightsbridge Green and Albert Gate conservation area audit (SPD, adopted 20 April 2009)

Each project starts with a feasibility visit and a measured survey. We then confirm which council covers the building, whether it is listed and who the landlord is, and read the lease with you. Our in-house architects draw the layout, services and floor build-up, and our in-house structural engineers design any change to a wall or floor.

Applications follow to the landlord, to Cadogan where a Licence to Alter is required, and to Westminster or Kensington and Chelsea where listing or planning calls for it. Work on site begins when those consents are in place, in the order already agreed for lifts, deliveries and the protection of common parts.

The same team stays with the project from the first visit to handover. Our in-house architects, designers and structural engineers draw and specify the work. Master joiners make the fitted furniture. Building Regulations approval comes from the building control body appointed for the project. Independent surveying is a separate appointment: Hampstead Chartered Surveyors & Building Consultancy, our RICS-regulated sister practice, is a separate firm that a homeowner instructs directly. One JCT contract covers the building work. Electrical and gas work is carried out by appropriately registered engineers. Completed structural work carries a 12-month aftercare/defects period. Cover is £5M public liability, £10M employers' liability and contractors' all risks cover. Main office: 250 Finchley Road, Hampstead, London NW3 6DN. Central London client consultation address: 2 Eaton Gate, Belgravia, London SW1W 9BJ. Telephone 020 7101 3168.

Licence to alter · Independent surveying by our sister practice