The Survey Report, titled "The Investigation and Analytical Survey of Silbury Hill" was based on the digital mapping data obtained in June 2001, i.e. on the extremely detailed surface mapping they obtained - as expressed in their famous green models. Using this, and old sources and photos they've produced a fascinating assessment of the archaeology, tracing the original form and the subsequent alterations and earthworks on the hill itself and in the surrounding area.

I seem to recall that the survey was said to be needed because there had been a collapse, and the stated purpose was to gain a fuller understanding of the hill as an aid to finding a solution. At the time, I thought that sounded pretty naive since, as any mining engineer will tell you, a surface survey will only tell you if the collapses have reached the top, in which case the game's up, and it's therefore rather advisable to investigate and rectify the voids rather than waste 1.5 years seeing if they have.

Be that as it may, the report as now presented is most assuredly NOT about the collapse. Instead, it's an enthusiastic embracing of all the new surface data for purely archaeological purposes. In 90 pages I can find not a single solitary reference to the fact that the thing has collapsed. If you didn't know it had then reading this report would leave you in the dark about it. How can that possibly be the case, unless it's deliberate?

I now have it from 3 separate sources that internal controversy has surrounded this report and caused an inordinate delay in it's release - 2.5 years late. I could speculate that it hasn't revealed anything useful about the stability (as it couldn't have) and that the delay has been because EH have been paralysed by embarrassment about the time and money that's been wasted. But that would be just speculation. Instead, I can point out a fact, and let others explain it: the survey was billed as part of a fact finding exercise as a result of the collapse, whereas the report is purely the application of the data to matters of archaeological interest. Something has changed and something is not right.