"BTW we don't know that he was an archaeo pro ,he just mentions being an ex undergraduate "

Very true.

Although, it has to be said there's a bit of a thread in conservation theory that gives a bit more weight to subsequent features than is maybe right. I guess a website that is focussed on prehistoric stuff might feel that in particular.

I did read a suggestion a while back that Atkinson's tunnels were now as valid a part of Silbury as the rest. I say - "yes in theory but bollocks in fact" ;)