Dominic,
from looking at the event site, I did notice the phrase:
"Help to create a massive stone labyrinth around the ancient Ryedown standing stone in time for the solstice sunrise"
put that way, it does sound more like the bewildering NewAgeVandalism that's getting more common ... Avebury, Men-an-Tol, Coldrum, they've all had it and lots more
yes, all stones are by definition ancient, but does this post mean that you know that the site is a bit of grass with a bit of stone on and no more, or that by dowsing you've determined the site *is* significant ... but surely if that is the case, is altering the site really the right thing to do?
Does that make any sense? Is it sacred or not? You're charging people to do something they can only do because the site isn't listed, but the significance of the event depends on the fact that it should ...
hmm
RG