Forming the southern edge of Boscubben is this 245 m long, straight boundary. It fossilises the terminal boundary of the possible Bronze Age (?) co-axial field system. The boundary varies considerably in form as it climbs the gentle western slope of Boscubben Hill towards Boscubben Carn. Starting at the West it begins as a Cornish hedge 85 m long, 0.8 m to 1.3 m high on the northern side, 1.0 to 1.4 m high on the external southern side. Its width varies from 1.4 to 1.5 m. An external (southern) ditch is 1.0 m wide, 0.2 m deep. A bank 0.9 to 1.4 m wide, 0.3 to 0.9 m high, and 80 m long, is succeeded by another Cornish hedge, 1.1 m wide, 0.7 to 1.1 m high, with an external (southern) ditch, 1.0 m wide, 0.3 m deep. After 53 m the boundary becomes a stone and earth bank with a dry stone wall built on top. There are two gaps in the boundary, the western is 4.0 m wide and has a modern wooden gate, with a land-rover track passing through. The other is a 2.0 m wide break, now fenced across by Mr Symons.