33, ST JAMES'S SQUARE SW1 (See details for further address information)

No. 33 St. James's Square is a terraced town mansion located on a corner site, built between 1770 and 1772 by Robert Adam. The building retains some of Adam's original interiors, while an eastern extension and rebuilding along Charles II Street were carried out by Sir John Soane from 1817 to 1823. The structure underwent heightening in the 19th century and alterations for use as a club and offices in 1911 by Edmerton and Gabriel.

The exterior is made of brown brick, with a stone facing added to the ground floor in 1911. The building features astylar facades and consists of three storeys, a 19th-century attic storey, a basement, and a dormered mansard roof. It has four windows wide on the St. James's Square side, with an 11-window return along Charles II Street, which includes five windows from Soane's addition.

A two-bay Ionic columned portico, added in 1911, faces St. James's Square, while a three-bay portico of the same design is found on Charles II Street. The windows are recessed glazing bar sashes, with those on the upper floors set under flat gauged arches. A continuous stone balustraded balcony runs along the first floor above the porticoes, and there is a guilloche plat band at the second floor. The stone main cornice is positioned over the third floor, with a stone dentil cornice below the parapet.

Soane's addition features a three-bay composition with narrow windows flanking a wide one, articulated by brick pilaster strips, while respecting Adam's design. The end bay contains a high carriage archway that once provided access to the Bishop of London's stables behind No. 32. Cast iron area railings surround the property.

Despite the interior alterations, many principal features from Adam's design remain intact in the first-floor rooms, including fine delicate ceilings (three of which are authenticated by drawings in the Soane Museum), friezes, doorcases, chimneypieces, and the apsed end of the former dressing room. Very little of Soane's work is still present.