Exterior
The S range is primarily of the C17, although remodelled in the C18 and altered in the early C20. Rubble stonework with a stone slate roof. Two storeys, attics and basement. The original build is the western two-thirds of the S front, comprising 4 window bays, the entrance in the second bay raised over 8 semi-circular steps and within a 2-storey porch. The opening is a chamfered segmental arch, and later openings in both sides. Oak doorcase with double ovolo mouldings running out at high set ogee stops. Inserted arch over door bearing the date 1632. The door is of 4 panels between moulded muntins, studded and hung on decorative hinges. Windows have segmental heads and stone sills, with later C20 timber windows and applied leadwork; surviving drawings show that the original glazing was of cross-frame type. Openings to the E of the porch (bays 3 and 4) have timber lintels. This build is extended by a further bay, probably C18, with similar but wider windows. Four hipped dormers. Above the outer arch of the porch is the sandstone arms of Williams, Enion Sais, a chevron parting three cocks, crest a cock and mantling, and inscribed SIR H.W. KNIGHT GLORIAM.DEO.CANO. Gable stacks c.1913; diagonally set linked brick shafts with a stone plaque at the base.
The main entrance front, facing W, is the early work of Sir Clough Williams-Ellis, who was commissioned in 1913, and continued to produce drawings until 1919. 'E'-plan, approximately symmetrical, with the end wings duplicated. Snecked coursed rubble with yellow Gwespyr stone ashlar dressings. Two storeys with parapet. Stone slated roofs with hipped dormers to attics.
Stone mullioned and transomed windows set flush to wall face, maintaining a degree of symmetry but having some regard to internal function. Central three-storey feature porch of high quality Gwespyr limestone ashlar in a personal French Beaux-Arts style. Wide giant pilasters with a tryglyph frieze inscribed ANN:DOM:MCMXIV, and attic storey with architraved window and lead cresting inscribed GR REG ANN IV. Hipped roof. Entrance between line-rusticated dies for pilasters; a low round architraved arch, with ribbon, symbolic plaques and pendants. Cross window with railed balcony to first floor. Symmetrical stone chimney stacks carrying tall paired brick shafts and yellow clayware pots.
The N wing of the 'E'-plan has an outer parallel wing projecting 1½ bays balancing the C17 wing on the S, with external gabled stack and shafts matching that of the S wing.
The E front, facing towards the river, is also approximately symmetrical. Two-storeys, canted end bays with a wider canted central bay, all rising from a wide raised terrace, with steps to the lawns. Over the central bay a rendered attic storey with a Venetian window and scroll supports. Eight hipped dormers.