A medieval deer park at Thonock has not been precisely defined on the ground although it may be at either SK 815916 or SK 822915. A park was attached to the castle, perhaps in two parts, both uphill and downhill. The park was already in existence in 1226 and in 1276 Edmund Earl of Cornwall was reckoned to have warren at Thonock 'ex antiquo'. The park seems to have included both wood pasture and coppiced woodland: in 1226 the Constable of Lincoln Castle was permitted to have 40 pieces of large timber, while in 1430 a grant of eleven acres and one rood of underwood growing in Thonock Park is recorded. A ditch leading out of the castle's south bailey ditch of the southwest towards the present east-west road from Corringham may represent the beginning of a park pale. More convincingly a low flat-topped bank running east-west and preserved in the tree belt along the north side of the Corringham Road at SK818914 is probably the pale. {1}