A shot in the dark: I hail from near Banbury, who's name is derived from the iron age 'Banner's Fort', after the chieften / mayor, whatever who established it. Could it be that there was a leader Aver?

It was probably used as a defensive site over a long period... Burl says that it was called "Waleditch" in 1289 - the moat of the Britons. Maybe it is the site of the battle of Arthur which trogs round this part of country looking for various venues.. Its very overlaid with Roman and Saxon history.. if you go into wordplay
Adams Grave =Wodnesbeorh
Wansdyke = Wodins ditch
Piggledean = pyttel-dentu Valley of the hawks
Chittoe = may have been coed-yw, (the yew wood)
and Sambourne, which comes from the celtic, as does Kennet, comes from sumina, which may have meant water.
Sorry going off track but Burl is always fascinating, but the roman road to Bath goes beneath Silbury Hill, and Sandy lane just up the road from Calne was one of the changing places for horses I believe. Perhaps all these early people were to superstitious to settle within the stones - that came later