Ah there's the problem of Stukeleys Evelavated drawings.
Most of his pics he seems to be floating 30ft in the air and he draws himself in his own pictures drawing the scene from the ground. (I'm off for a quick lie down...)
I didn't think that Silbury would be visible from WB circles so I went there and Bloody El! You Can see Silbury, but not from the field with the stones in.
Dave Field wrote in the last issue of WAM that he thinks the Circles were actualy at another site on higher ground.
The WB Circles Site on OS maps is actualy a natural sarcen drift.
Just to complicate things I think the drawing is from Beckhampton Penning.
PeteG