No.11 and Attached Railings

This is a house built around 1790-1793, with alterations in the 19th and 20th centuries, originally designed by John Palmer. It is constructed of limestone ashlar to the front, with a rubble basement and cement render to the rear. The roof is a mansard style with Welsh slate, a coped gable wall on the left side, and two rebuilt ashlar stacks shared with the adjacent property at No. 10 Park Street.

The house has three storeys, an attic, and a cellar, presenting a single bay with a three-window front. The first floor has three 19th-century plate glass sash windows with horn detailing and stone sills. The second floor mirrors this arrangement. The ground floor features two plate glass sash windows with horn detailing and a stone sill, alongside a six-panel front door with reeded and raised panels, two glazed upper panels, and a late 18th or 19th-century oval iron knocker within a Doric doorcase. The basement has two six-pane sash windows, a plank door with a two-light overlight set within an ashlar surround, and the original area steps have been removed. A double dormer window with a single plate glass window is present; one side is blocked. Architectural details include a band course above the ground floor, a lintel, a moulded eaves cornice, and a coped parapet. The rear elevation has six-pane sash windows on all three floors, a single six-pane and one plate glass window in the double dormer, a 19th-century hanging extension to the first and second floors, and a single-storey ashlar extension with a flat lead roof at ground floor level.

The interior has not been inspected. The property is accompanied by attached railings and a gate with urn tops on limestone bases. It was part of an incomplete development of St James's Square, on land leased in 1790. Work on Park Street began to Palmer's design and continued, but was not completed to the designs of John Pinch after 1808. Originally, the street ended at All Saints Chapel and was planned to be extended as Regent Place.