3, Cavendish Square W1

No. 3 Cavendish Square is a substantial terrace house built around 1740. It features a brown brick exterior and a slate roof, rising four storeys with a basement and a slated mansard roof that includes dormers. The building has four windows, with stone plat bands and a main cornice at the third floor level. The sash windows are revealed and have red brick dressings and gauged flat arches. There are early 19th-century cast iron balconettes on the first floor and a large stone architrave doorcase with console brackets supporting the cornice. The property also includes cast iron area railings.

Inside, the house has a well-crafted staircase in the front compartment leading to the piano nobile, featuring dado and full-height panelling. The staircase has an open string design with carved tread ends, twisted balusters, a ramped handrail that scrolls at the foot, and columnar newels. The panelled drawing room has entablatured doorways, and there are marble carved chimneypieces in both the front and rear rooms. Additionally, there is a service staircase with a turned baluster off the rear vestibule.