No. 3 and Attached Railings

No. 3 Marlborough Street is a terrace house completed in 1791, with alterations from the 19th century. It was designed by John Palmer and built by William Reeves. The front is faced with limestone ashlar, painted to the ground floor, while the basement is of rubble with traces of old lime wash, and the rear is of rubble. The house has a double-pile, parapeted mansard roof covered with Welsh slate to the front and double Roman tiles to the rear, with a coped party wall to the left, featuring a large ashlar stack with some early clay pots. A staircase is located to the front.

The house is three storeys, with an attic and cellar, and has a two-window front. The first floor has two plate glass, horned sash windows within plain reveals. The second floor has two six/six sash windows in plain reveals with stone sills. The rear elevation features plate glass, horned sashes to the lower floors, six/six sashes to the second floor and a double dormer. The ground floor has a plate glass, horned sash window to the left, a six-panel door with reeded and fielded panels and a single glazed panel, within a timber doorcase with a moulded architrave, panelled pilasters with console brackets, and a moulded cornice. A pennant paved crossover, flush with the pavement, includes a cast iron footscraper. The basement has a six/six sash window, a 19th-century half-glazed door, and a single-light window within an ashlar infilling. Dormers have been altered and linked.

Architectural details include a timber bressumer and a stone band course over the ground floor, a weathered sill band to the first floor, a frieze, a moulded eaves cornice, and a coped parapet. The left side has a lead hopperhead and largely lead downpipe. The interior of the house was not inspected. The house has attached wrought iron railings with cast urn tops on limestone bases.

It forms part of an incomplete development surrounding St James's Square, on land leased to Fielder, King, Hewlett and Broom. A lease was granted to William Reeves on 4 March 1791 for 96 years from 24 June 1790.