12, Marlborough Street

No. 12 Marlborough Street is a terrace house, dating from approximately 1790 to 1793, with alterations from the 19th and 20th centuries, designed by John Palmer. The front of the building is faced with limestone ashlar, with the right side and rear also in limestone ashlar, partially painted. It has a Welsh slate, parapeted mansard roof, hipped on the right-hand side, and a coped party wall to the left, which incorporates a single large ashlar stack shared with No. 11 Marlborough Street.

The house is situated at the junction of Marlborough Street and Julian Road, and is wider at the front with a splayed corner to the right where it meets Julian Road. The front has a four-window, two-bay façade over three storeys, with an attic and a basement. The first floor has a Venetian window on the left, alongside a plate-glass, horned sash window to the right. The second floor features three grouped plate-glass, horned sashes in plain reveals with a continuous stone sill, and a similar sash to the right. The ground floor has an eight/eight horned sash window in a splayed reveal with a stone sill on the left, and a six-panel door with beaded and fielded panels, glazed sections, and a 19th-century brass door handle within a pedimented Doric doorcase with a single concrete paved step. The basement opening below the ground floor window is infilled with glass bricks. A double dormer has plate-glass sashes. A timber bressumer sits above the ground floor window on the left, with a stone band course above the ground floor, featuring an iron strap, a frieze, a moulded eaves cornice, and a coped parapet, with a lead hopperhead to the right side. This band course, frieze, cornice, and parapet are continued to a blind, splayed corner on the right. The right side, facing Julian Road, contains a plate-glass, horned sash window with a stone sill on the first floor, a larger and smaller window on the second floor, and two similar glazing bar sashes on the ground floor. Two small openings are visible in the basement. There is a band course above the ground floor, incorporating an iron strap, a small eaves cornice, and a coped parapet. The rear elevation includes 19th and 20th-century sash windows, with an iron strap above the ground floor level.

The interior was not inspected during the listing process. The property is part of an incomplete development near St James’s Square, which was built on land leased from Sir Peter Rivers Gay on 25 March 1790 by Fielder, King, Hewlett, and Broom. Marlborough Street serves as one of the four diagonal approaches to St James’s Square.