In my web wanderings about this the other day I found a flint knapping site. Apparently the nodules arn't big enough to make into a handaxe, you need to get to where the flint becomes a sheet, hence why they dug down so far at Grimes Graves. Now I've no idea of the geology of the hill, but I'm presuming there is sheet flint* on the hill else why would there be mines at all...

Oh and I'll be back that way tomorrow sometime around midday after I finish off Kent, so I'm gonna 'walk' the cursus!