91, Harley Street W1

No. 91 is a corner terraced house located on Harley Street, built around 1774-1776 and altered in the mid-19th century. It was part of the Portland Estate development by John White in collaboration with the plasterer Thomas Collins, who were associates of Sir William Chambers. The building is constructed of stock brick with a heavily rusticated stucco ground floor and features a slate roof. It has four storeys, a basement, and a dormered mansard. The façade is four windows wide, with a three-window return to Weymouth Street, two of which are blind.

The entrance is a semicircular arched doorway on the left, framed by a rusticated and vermiculated surround, featuring a panelled door, sidelights, and a fanlight. The upper floors have recessed sash windows under flat gauged arches, with stucco keystones on the third floor. Additional architectural details include a first-floor plat band and sill band, a plat band on the second floor with a block bracketed cornice above it, a sill course on the third floor, and a stone-coped parapet. The return side has similar details, with a mid-19th century stucco bow window added to the ground floor and a chimney stack that rises from the parapet.

A cast iron balcony from the mid-19th century spans the first floor on brackets, and there are cast iron plumbed spike area railings. The interior retains some features of the typical plasterwork associated with White and Collins, as well as a top-lit geometrical stone staircase with a later iron balustrade.