No 6 and Attached Wall to the Rear

House, since around 1920 part of a nursing home, now vacant. Built 1723-1728 for James Brydges, Duke of Chandos, designed by Benjamin Holloway or Fort and Shepherd, the Duke's London surveyors.

The building is constructed of Flemish-bond brick with painted Ham Hill stone detailing. It features a moulded coping to the parapet, a cornice, a rusticated quoin to the right, architraves and doorcase, and a double Roman tiled roof with brick stacks to the gable ends. The roof structure is double-pitched with the space between the ridges filled in.

The house has three storeys with a cellar beneath, and a double-depth plan with a 19th-century two-storey rear wing to the right. The principal front is symmetrical with a five-window range. A band of yellow brick runs horizontally across the building between the first and second floors and below the parapet. The windows are 6/6-pane sashes with some original crown glass, set within cyma-moulded segmental-arched architraves carved from rectangular blocks, with moulded cills and brackets on most windows.

The main entrance is at ground level, accessed by three steps, with a six-panel door dating to the 20th century set beneath a segmental-arched overlight. The doorcase features a projecting dentilled cornice supported by fluted Ionic pilasters and a cyma-moulded architrave. To its left is a small segmental arch to the cellar. The right return has a semi-elliptical arch to the cellar and a blind stack corbelled out above ground level and rising across three blind windows on each floor to the left. At the centre of the right return is a plain Ham Hill stone architrave to a blocked door set well above street level, suggesting former steps once reached it.

The interior retains substantial early 18th-century features. The rear of the front door has plain panelling with wrought-iron L hinges with spear-head ends and a large lock. The main hall contains an early 19th-century semi-elliptical arch to the rear stair hall and high skirting. The staircase to the left of the central hall has an oak wreathed handrail with a curtail step to the first flight; the stairs to the second floor are early 18th-century painted oak with a closed string, turned balusters and newels, and a moulded swept handrail.

The ground floor rooms retain panelled shutters and dado rails. The front right room features full-height raised-and-fielded panelling with bolection moulding over the fireplace and wide panels to the rear wall, a box cornice, and simple bead-topped skirting boards with wide oak floorboards. A mid-19th-century painted wood fire-surround has a wide mantelshelf supported by moulded consoles and recessed semicircular-ended panels. A jib door with a semicircular arch leads to a cupboard. The room has a 19th-century foliate ceiling rose. The front left room has full-height wide panels continuing narrower into segmental-arched recesses flanking a late 18th-century Adam-style fireplace with moulded cornice, a frieze of wheatear swags between vases and oval patera, purple and grey marble with white marble intrados and a fluted-inlay keystone, with early 20th-century brown glazed tiles to the inner surround.

The first floor retains similar panelled shutters, dado rails, and full-height raised-and-fielded panelling in several rooms. The front right room has a small blocked stack to the corner. The front left room has panelling with bolection moulding above a heavily moulded fire-surround with a mantelshelf and late 19th-century Art Nouveau-style glazed tiles to the grate, with a thin two-panel cupboard door to the left. The rear left room includes a box cornice.

The second floor has three rooms to the right, with the central room featuring a heavy chamfered lateral beam. The rear left room has an early 18th-century planked partition to the passage and a square stone fire-surround with moulded exterior and curved inner corners. The rear wing retains a repositioned early 18th-century window to the first floor.

The terraces of houses in Castle Street form an important architectural group, unusual for their scale and ambition outside London's West End.