I'd be surprised if the actual figure has leaked out, it must be one of their most sensitive secrets, and is certainly one of the things removed from the Commission Meeting minutes for "commercial reasons". Not that it matters, the cost must have been astronomic, whatever it was, to employ a firm of that sort for such a long time.

I've wondered whether it has proved to be wasted money for some time, and they've sort of admitted it by saying it was "inconclusive" and they needed further investigations. Of course, from my perspective it's been a waste of money all along, but even from theirs it now seems it has been.

But worse still, against the background of their overall duty to get the best advice, I think there are grounds for wondering whether they even did so:

Skanska are famous for constructing a lot of the channel tunnel and the deepest mine in the world in South Africa, but I can't find anything they've been involved in that is relevant to Silbury. Experience of mine consolidation would seem to be the main requirement. Britain has lots of such specialist firms yet they lost out in the competitive tendering process. The unique selling point of Skanska seems to have been their new 3D scanning technique, licensed from a US firm, which was held up by their spokesmen as enabling the voids to be displayed visually and in great detail, whereas boring old conventional scanning would also locate the voids but the display would be less user friendly. Totally unnecessary in my view, though entirely desirable from the mistaken perspective of EH that the voids needed to be precisely mapped.

Yet worse still, I can't find any evidence that 3D tomography has previously been road-tested in a Silbury style context. Indeed I can't find much evidence it had been used much in any context. It's very new. The fact that it hasn't proved satisfactory now seems to be self-evident. Are we in a situation where EH have turned their backs on standard mine consolidation firms in favour of a new and untried system, that turns out not to work, all for the sake of getting a level of detail that was itself misconceived and unnecessary? Surely not, they wouldn't treat a national treasure like that would they?

My apology to them is ready to post, once they publicise how I've got the wrong impression. Failing that, Pete, you would be well justified in asking your local MP to investigate whether public funds have been properly expended.