No. 4 and Attached Railings

This is a house, now converted into flats, completed in 1791 with 20th-century alterations. It was designed by John Palmer and built by Richard Sartain. The front of the building is faced with limestone ashlar, while the rear is of rubble construction. It features a Welsh slate, double-pile, mansard roof with a coped gable wall and two ashlar stacks to the left. The house is wider at the rear, with a staircase positioned at the rear.

The building is three storeys high, with an attic and basement, and has a two-window facade. The first floor has two 19th-century plate glass sash windows with hornets, set in plain reveals with stone sills, and wrought iron balconettes. A small squint window sits to the right. The second floor mirrors this design with similar sashes. The ground floor has two matching sash windows and a six-panel door with raised and fielded panels and a single glazed panel above, set within a pedimented Doric doorcase. A single step leads to a pennant-paved crossover with a wrought iron footscraper. The basement has a six/six-sash window in a plain reveal and a stone sill, alongside a 20th-century door within an ashlar infilling, and 20th-century area steps. There are two dormers with two/two-sash windows. Architectural details include a band course over the ground floor, a frieze, a moulded eaves cornice, and a coped parapet.

The rear elevation features three 19th-century sashes to the ground floor, narrower on the left and right, and to the first and second floors to the right. A wrought iron balcony with a lead roof sits on the first floor. Two 19th-century sashes are located in the basement; and two six/six sashes illuminate the staircase which angles away from the main facade. There are a single and two triple dormers with 19th-century sash windows. A lead hopperhead is present on the left side.

The interior has not been inspected.

Attached to the building are wrought iron railings and a gate with cast tops on limestone bases.

This house was part of an incomplete development of St James's Square, constructed on land leased in 1790. Lower Park Street forms one of the diagonal approaches to St James's Square. Richard Sartain held an underlease for 96 years, starting in 1791.