This has been sent to me,
The 'Druid's Barrow' was located in the 1993 Kennet Valley Foul Sewer pipeline at SU 10606830, the exposed part (well north of the current road) being excavated by Wessex Archaeology. It was published in: A Powell, M Allen, I Barnes (1996) Archaeology in the Avebury Area, Wiltshire: recent discoveries along the line of Kennet Valley Foul Sewer Pipeline, 1993. Wessex Archaeology Report No 8.

They reproduce one of Stukeley's views of Avebury as the frontispiece, showing the 'Via Badonica' cutting through the barrow at the southern end of 'Windmill' (ie Waden) Hill.

PeteG