Littlestone wrote:
...but it is actually sited on a slightly higher natural platform could also have been sited even lower in the Kennet valley with greater" multiple sightings " points.
Not quite. The confluence of the Winterbourne and the Kennet is maybe the lowest point in the immediate area, and then the land gradually falls away from the Swallowhead. It’s not much of a fall, and I’m not sure how much of a difference it would make to seeing Silbury from the many vantage points you can see it from today, but I bet you’d no longer be able to see Silbury from within the Avebury circle if Silbury had been constructed in the field between the road and the Swallowhead.