Acton Castle

Acton Castle is a country house built around 1775 for John Stackhouse, the eminent botanist, with extensions added in the later 18th century and again in the late 19th century. It is constructed of granite and elvan ashlar with dressed granite details, featuring grouted hipped scantle slate roofs behind embattled parapets and dressed granite embattled chimneys over projecting corner piers.

The original structure comprises a central 2-room plan 3-storey block over a service basement, with a central large stair hall between the rooms. Around the later 18th century, two identical 2-storey wings were added at either side, each wing 2 rooms wide with octagonal rooms at the far left and far right. All elements are built in similar classical style but incorporate battlements and other medieval-style details. Around the late 19th century, service rooms were added behind the original block and a circular stair tower with a granite newel stair was added behind the right-hand wing.

The exterior presents 3 storeys over basement for the main block, flanked by 2-storey wings. The south front displays a 2:3:2 bays arrangement, with the central 3 bays and clasping turrets broken forward and rising above the parapet with battlements; the sides and rear are similar to the front but partly concealed by the 19th-century range. The wings have canted front bays at the far left and right. The basement is granite ashlar as a plinth with elvan ashlar above; mid-floor bands break forward on parts of the main block and wings, and a moulded cornice runs to the embattled parapet over the central block. Battlements survive over the wings only where they crown the octagonal bays. Tripartite windows appear throughout all bays; those of the main block retain their original granite mullions supporting the springing for flat arches over the middle lights, with original hornless sashes to the first floor. The wings have iron casements in openings with sills lowered around the 1930s and replaced granite mullions. Flanking the windows of the bays are blind cruciform pistol loops, which also appear on the other faces of the octagonal ends. Small window openings, cut in the 20th century, appear on the front of the wings on either side of the main block.

The interior retains the original stair and a complete 18th-century room to the left of the entrance, along with 18th-century floors, what is likely 18th-century roof structure, and other 18th-century features including panelled doors. The stair has an open well and open string with slender turned column balusters and a ramped mahogany handrail. The left-hand room features panelled walls and a ceiling cornice with triglyphs, along with an eared Adam style chimneypiece. The right-hand room contains a circa mid-19th-century moulded ceiling cornice with robust egg and dart over bead and reel and a carved trailing band. Linking the first floor rooms at the rear of the stair hall is an axial passage with a circa late 19th-century barrel vaulted ceiling with bold ribs. The ground floor rooms of the wings are now large rooms.

Stackhouse used this house as a laboratory for his research into marine life, particularly seaweed, and it is possible that the wings were built to serve this purpose. Acton Castle is similar to The Manor Office (formerly Trevelyon House), Marazion, and Tregenna Castle, St Ives, both dating to around 1775 and possibly by the same architect, John Wood the Younger.