Gatehouse to South of Trewane and Garden Walls to South West, South, South East and North East

The gatehouse to the south of Trewane and the garden walls to the southwest, south, southeast, and northeast were built around the early 17th century, with some 19th-century work that reused 17th-century materials. The structures are made of stone rubble with granite dressings. The garden walls enclose the garden in front of the house and extend around a raised terrace to the east and to the rear of the house on the northeast. There are two reset early 17th-century four-centred granite arches in the walls near the front of the house on the southwest and southeast, along with a third reset early 17th-century four-centred granite arch in the rear wall to the northeast.

To the south of the house, aligned with the central entrance, is the gatehouse, which may have been built in the 19th century as a folly using early 17th-century dressed granite. It consists of the front and side walls of a two-storey roofless building set into a steeply sloping bank. The ground floor, which is below the ground level of the house and gardens, features a one-light mullion window in the left-hand (west) wall. A flight of steps, mainly made of reused granite chamfered jambs and mullions, leads up to the large granite segmental arched entrance on the first floor. This arch is directly opposite the central entrance of Trewane and creates an impressive gateway.