One last excavation was sanctioned and a team from Newsnight joined it in its final stages.
The historians have uncovered arrowheads, and dense, stony antlers which were used as tools.
They now know that Silbury didn't go up all at once but in three stages. Deep inside the hill, beneath up to half a million tonnes of ever so slightly unstable chalk, we goggled at the perfectly preserved fronds of moss which had grown four millennia ago on the slopes of the original mound.
Silbury Hill must have been a stunning sight when it was free of moss and grass and was just a mound of chalk. I would think there would be steps built into the chalk somewhere, but what I've read doesn't mention any.
The movie clip provided is pretty good.