66, St James' Street

66 St James' Street is a town house that has been converted into offices. It was built in the early 18th century, with alterations made around 1800 and in the mid-20th century. The building is constructed of brick, featuring ashlar dressings and a stucco ground floor and parapet. The roof is not visible, and there is a brick side wall stack. It has an ashlar plinth and a wooden cornice with modillions. The structure is four storeys tall and has a three-window range of 12-pane sash windows with keystone wedge lintels. Above these, there are three smaller similar windows, and at the top, a central 6-pane sash window. On the ground floor, there is a 20th-century panelled door with a fanlight to the left, and to the right, a two-light casement window with a stucco mullion. There are also two segment-arched cellar openings.

Inside, the building was altered around 1800 and features an original dogleg stair with four flights, turned balusters, and intersecting strings. From the half-landings, there are winder stairs leading to a rear wing, which has stick balusters and ramped handrails. The ground floor room contains a late 19th-century marble fireplace flanked by round-headed recesses, one of which has cupboard doors. The rear room includes a 19th-century kitchen range with a wooden surround. Other rooms feature 19th-century fireplaces and several two and six-panel doors. The basement has elliptical arched brick cellars and stairs leading to deeper rock-cut cellars.