Warn't me that did the Avon valley research. I think we found a paper showing what the landscape was like at that time. Cores? No doubt the new route-lookers will find that too.

"I seem to recall our concrete block was not the full 40 tons of the prototype". 17 tons I think, which is 3 or 4 blue stones so not bad.

I do recall uphill was a swine, but still just do-able, until the local tug-o-war team helped the townie megalithomaniacs and the thing shot up the hill at a hell of a lick and straight off the rollers without an appreciable loss of speed! It taught me brute force is best.