It certainly brought people together for a cause HSD that's for sure! Interesting that you should mention the WKLB which was built over a 1000 years prior to Silbury Hill. As the long barrow was 'closing down' so the building of SH began, or possibly as one belief ran out of steam another commenced as this was a pivotal point in time. The hill rose up to level the height of the WKLB and lodged between the two was the River Kennet and the Swallowhead Springs. Coincidence?

From the other end of the spectrum- i was once there at night with a friend and we both felt separately that it was a big plug put there because of something terrible that had happened, i dismissed this out of hand until i got home and the first thing i read [ i think it was in a book about mystics and glastonbury ] that others had thought the same thing, this of course doesn't make it any truer but i remember thinking how odd other people had experienced the same feelings as us.