"I can see that some will be able to argue that this (hopefully) will be the last time the hill is interfered with and that it is therefore of paramount importance to learn as much as we can with today's techniques"

... and I might agree with them, it's a noble sentiment.... providing it's not at the cost of otherwise avoidable major loss to the fabric.

But from all I've read, there may be a choice available: we can bequeath knowledge to the future at the cost of major loss or we can decline to do that and and bequeath a monument sans that major loss.

EH say there is no such choice available, Silbury MUST bear the loss and the knowledge gathering is an incidental compensation. My modest request is that they must explain very clearly to the public how that opinion is supported by the published facts.