Nope, but I thought some of us could check it out at the Megameet (it's just an idea and I don't mind being proved wrong :-)

I think it might have been me that put this in your mind when we met there. Sorry ;)

I have to say though I recall reading the water table has jumped about a lot over the millennia so I don't think any speculation about water courses is necessarily wrong. Ditto the nearby prehistoric settlement. As the geofizz near Silbury shows, wherever you look you find round there.