There's more. EH cannot claim that the report WASN'T about stability, because there's a chapter about it. Not about instability arising from excavations though. About it's inherent instability. It's a very short chapter, 1.5 pages out of 90, and rather strange and incongruous in that it appears straight after the chapter titled "Discussions and Conclusions", almost as if.... well, write your own script.

Did you know about Silbury that it's a surprise "that it's held together so well"? and that "there must be a reasonable chance that there will be further erosion" and that "weight on the natural chalk surface must be enormous" and "should part of the inner edge of the ditch give way a sizeable portion of the mound may follow"? I'm not saying monuments don't erode, but it does seem to me that this is over-the-top speculation, for effect, almost like an insurance policy. Bear in mind, this speculation is on the basis of a surface survey only. So what makes Silbury's inherent instability more worthy of such comments than the equally grassy but steeper slopes of Avebury, Oldbury, Danebury etc?

Perhaps I'm being over sensitive. But get this: "It is not unknown for large monuments to encounter this process", fair enough, but "similar examples ONLY come from other parts of the world" Oh really? So the collapse of Marden doesn't count, as it was caused by an untended excavation shaft? So we must instead scan the world to prove the point that Silbury may be inherently unstable must we? Yes we must, and it turns out we have to totally scrape the barrel: the pyramid of Meidum in Egypt (made of sand!), the ziggurats of Iraq (made of mud bricks), and Monks Mound, USA (made of alternating layers of clay and sand!)

In my opinion this report gives every appearance of having been very well written by professionals but subsequently meddled with and spun.