"revised grid ref for the crossing points of Silbury - Sanctuary and W Kennet -Falkner's Circle = SU 10527 68437 . Is that close to Silbaby ?"
Silbaby on TMA is given as SU106683, but we're at cross purposes. I'm not an advocate of the Falkners-Silbaby-WKLB line - Falkners is over the hill, not visible so they'd need to be amazing surveyors and have a very wierd attitude ;)
That line just happenened to be on the map I linked to. My real interest is the visible one, S-S-S.
Silbury 2 is where Silbury is - its much smaller previous version.