11, HILL STREET W1 (See details for further address information)

No. 11 Hill Street is a terraced house dating from approximately 1748, with alterations and a refronting in the years 1907 to 1914. A rear left-hand extension, containing a ballroom, was added in the early 1890s, possibly designed by Robert Edis for the Duke of Newcastle. Stables at the rear were constructed around 1906 by J Leonard Williams for Charles Ansell, who also designed a garage, now No. 4 Hays Mews. The house, stables, and garden wall combine to form a courtyard.

The main house is built of red brick with limestone dressings, and has four storeys, a basement, and attics. The roof is a slated mansard with dormers. The prominent entrances have moulded surrounds, console bracketed hoods, and panelled, part-glazed doors with intricate wrought iron scroll grills. Ground floor windows are sash windows within architraves with keystones. The first floor windows have architraves with alternating triangular and segmental pediments, and a continuous wrought iron balcony. Second-floor windows feature triangular pediments, and third-floor windows have architraved cornices. A parapet tops the facade. The courtyard facade has a glazed loggia with three arches, above which are three round-arched casements. A three-light projecting bay window projects from the third floor. A central entrance to the loggia leads to an impressive imperial staircase, consisting of two curved flights and a straight section, with a cast iron balustrade.

The stables are two storeys high. Their courtyard facade is stuccoed, with two round-arched ground floor sashes in shallow architraved recesses, linked by impost bands. The first floor has four sashes with panelled aprons, separated by Tuscan pilasters carrying an entablature with a bracketed cornice and surmounted by a cast iron balustrade. The mews facade is of red brick, with stone detailing at ground floor level and pilasters supporting a cornice and stone parapet. It has a tiled mansard roof with dormers.

The interior has undergone considerable alteration and partitioning. Elements of a sumptuous redecoration in an English Carolean style, implemented around 1906 by J Leonard Williams, remain, including a satin-wood dressing room, now painted over. A later decorative scheme, incorporating some of these features, appears to date from the late 1920s or early 1930s. The main staircase is in a provincial early 18th century style and was likely constructed around 1920. The ballroom in the rear left-hand extension is in a Louis XV style, built for the Duke of Newcastle, and features his monogram and ducal coronet in the coving. It is characterized by a marble column screen, a musician's gallery with three openings and decorative wrought iron railings, and high-quality decoration in blue, gold and white, incorporating musical instruments and floral swags. Round-arched window recesses are also present.

No. 11 Hill Street forms a group with Nos. 5-19 (odd) Hill Street and No. 4 Hays Mews.