I know a little about the Walton Basin, mainly because I have a copy of The Walton Basin Project: Excavation and Survey in a Prehistoric Landscape 1993-7 by Alex Gibson.
http://www.britarch.ac.uk/pubs/prehist.html
It does state that the Hindwell pallisaded enclosure is *by far* the largest Neolithic enclosure in Britain, however, there`s an even larger one at Urmitz in Germany.
baz