21, Upper Brook Street W1

No. 21 Upper Brook Street is a terraced town house built in 1737, with alterations and internal remodelling dating from around 1787 to 1800, and restoration and stuccoing of the front completed in the early 1970s. The building features a stucco exterior and a slate roof, standing four storeys tall with a basement and a dormered mansard. It has three windows across its façade. The ground floor is channelled stucco, with an entrance on the left that includes a late 18th-century semicircular doorway flanked by narrow sidelights and topped with a patterned fanlight. The windows are recessed, square-headed sash types. The building has a parapet with coping and is adorned with late 18th-century wrought iron area railings.

Inside, the house retains features from its late 18th-century remodelling, including cornices, friezes, and some doorcases. A pair of columns separates the front and back rooms on the ground floor, and there are several marble chimney pieces, all reflecting a restrained style reminiscent of Henry Holland. The staircase, which has a wrought iron balustrade, is believed to have originated during this decorative campaign, although it likely took its current form during alterations in the late 1880s.