In reply to monkeymark:
I was there Friday afternoon and saw a couple of transit style flatbed vans as I drove away. One came in the car park as I was packing up, the other 2 were just driving along Holt Ln, so can't be sure they were headed to Denham.
I thought it was odd there were so many around, but figured they were just tradesmen using the car park for a quiet afternoon brew (which these ones may well have been doing)! Didn't pay too much attention if I'm honest, so can't remember the colour.
I didn't go down to the overhangs either, so didn't see this whether any of this had already been started. But what I really don't get, is if they want what is essentially a manufactured climbing wall, why don't they go to a climbing wall or find some wall with appropriate brickwork? I may make a point of going more often now.