Sorry, I've just realised I didn't tell you what “The Wilmington Giant” says about the flint mines.

Castleden writes about them under the assumption of a Neolithic origin. On page 132 he comments that most Neolithic flint mining occured in the "flint-rich Actinocamax quadratus zone of the chalk", about one third of the way down the scarp slope, whereas on Windover Hill they worked the "Micraster" zone. This also, he says, seems to be the only place where the principle escarpment of the Downs was worked.

He speculates that this might have been due to the significance of THAT hilltop. One could also say that it might imply a lack of Neolithic expertise of course.