Plumpton plain is situated on the top of the South Downs, roughly 600 feet above sea level, six miles north-east of Brighton and four miles north-west of Lewes (fig. 1). From its western end a broad spur slopes gently southwards from the northern escarpment of the Downs, lying between Moustone Valley on the south-east and Faulkners Bottom on the west. Most of this Downland is covered with a dense scrub of gorse, thorn and bramble, and with large patches of bracken and heather. A series of broad paths running roughly at right angles with one another has been cut through this vegetation to facilitate the preservation of game. Along the main ridge of the spur running north and south is a broad gallop which, at a height of 600 feet O.D., passes through a group of earthworks situated 1500 feet from the north edge of the Downs and 2300 feet east of Streathill Farm. This group was the primary object of bur investigations and will be referred to as Site A (fig. 2).

Site B (fig. 3) lies a quarter of a mile to the south-east of Site A on a small lateral spur jutting between the twin heads of Moustone Bottom. The only visible evidence of prehistoric occupation was a quantity of coarse gritty sherds and calcined flints on the surface to the south-east of a low bank and ditch which runs across the spur.

Several groups of lynchets enclosing square Celtic fields are to be seen in the neighbourhood of these two sites. They lie principally to the south-east of Site A and to the south of Site B.