Evaluation and subsequent excavation by T Carew of PCA in advance of the construction of a new prison. A palaeochannel, probably dating to the late glacial to early post-glacial period, cut through the centre of the excavated area. A probable early Mesolithic flint blade was recovered from near the channel, although it was found in a later context. The earliest of the cut features was a pit with a probable placed deposit of early Neolithic flintwork. This was adjacent to a middle to Late Neolithic ring ditch, interpreted as either a hengiform monument or a barrow. Elsewhere on the site, a number of ditches formed an extensive field system with at least four prehistoric phases represented, probably starting in the Bronze Age. A middle Iron Age settlement was revealed clustered around the Neolithic ring ditch, and consisted of nine roundhouses, including a pair that formed a figure of eight structure, about seven four-post structures, and pit groups, and a possible corral. In the Roman period the field system was extended, demonstrating continuity of use. A rectangular post-built structure with an internal division was also found, and could date to the Neolithic, Late Bronze Age, or Saxon periods. The continuity of the orientation of the ditches throughout the history of the site may relate to the topography which consists of areas of slightly higher ground --- where all the domestic and ritual structures were found --- and lower areas towards and around which the ditches drained.