Medieval Assize Rolls of 1289 describe the henge itself as Waledich, which has been interpreted as meaning 'ditch of the Britians'. <snip>
It is equally likely however , that the name simply means 'Wall-Ditch, as a literal interpretaion of the bank and ditch of the henge; an instance of the place name Walditch in Dorset, for example, is thus explained (Ekwall 1960, 492)
From Avebury a biography of a landscape by Pollard & Reynolds p203-4.
PeteG