Cersselly House was built c.1770 for John Bartlett Allen, the wealthy owner of local coal mines, and recalls the work of principal architects of the period, e.g. Keck at Penrice (Gower). The first changes to the house were made in 1816-18 when the present staircase was built. Subsequent alterations are most notably the wings added in the 1860s; about the same time the park was remodelled and many estate buildings erected.

The c.1770 main block has a symmetrical, 3-storey, 5-bay coursed rubble front, the central three bays of which are advanced; freestone quoins, band courses and window dressings. Slightly set back to either side are 2-storey, 3-bay wings that relate to the 1860s enlargement and have uncoursed rubble elevations and simpler dressings; the porch is also of this period. The building has hipped slate roofs and tall stone chimney stacks; moulded eaves to the main block and wider boarded eaves to the wings. There are small-pane sash windows throughout; The porch has twinned pilasters and round-arched openings with dropped keystones to each side; the wings have splayed bays with dentilled cornices and balustraded parapets.

Notable features of the interior include the drawing-room, the finest room in the house, occupying the full width of the bay on the garden front. It has a finely executed Rococo plaster ceiling, the decoration of which includes an egg and dart cornice and a cartouche with musical trophies together with an open score. This room also retains a fine marble chimneypiece and has silk wall-hangings and panelling from the Edwardian period. The library has fine mahogany bookcases.

Reference: Cadw listed buildings database.