Alton Priors 2
Image by notjamesbond

>> but the stones just seem to have been used there without any symbolic gesture of assimilation

I would say that using them for the entrance could be particularly symbolic

> I would say that using them for the entrance could be particularly symbolic

Yeah... didn't think of that. Alternatively, the stones could have just been seen as a ready source of building material - just as they were at Avebury.