What you need to do is find earlier iron age evidence of a shrine, which means digging... both the rivers and Swallowhead are dry some of the time, thats why wells were dug by the romans at the foot of Silbury, if they were throwing in votive offerings like they did at the Bath spring, they were requesting something of the gods.
Precisely, hence the title of this thread and my comment above - "Perhaps any future investigations/excavations should start at Pan Bridge and work upstream across the Silbury floodplain towards the Winterbourne (as well as downstream towards the Kennet)."Have just read your latest blog entries and the one on Groundwell Ridge is particularly interesting (in relation to Silbury) -
"Groundwell Ridge Roman Villa at Abbey Meads, discovered in 1996 may well be the site of a roman healing sanctuary, it lies close to the Roman road which runs between Swindon and Cirencester, and has a complex of shrines, pools and terraced gardens and was visited by pilgrims between AD100 and 350, information can be found on the above at English Heritage."