No retroclaims (yet) so thought I'd post up.
Caveats: might need a downgrade; maybe also not as good as I think it is but I thought it was brilliant.
Horrible social media splooge with photos and video here:
https://www.instagram.com/p/CL86WTnDeLVhttps://www.instagram.com/p/CL69NLDD2Ic/Approach and access beta is as follows:
Park at Stephen Smith's garden centre in Harden. Cross the road and go over a stile to a footpath. Follow this to a track and turn left, then immediately right and pass two broken down walls. Follow this track up into the woods to reach the Folly Boulders in about 8 mins (guide on Unknown Stones. Some really good stuff there). From the Folly Boulders continue deeper into the woods along the top track. As the track descends, an old ruined wall will appear on the left running down the hill. Follow this downhill for 30m or so. The boulder is just on the far side of the wall, 5 mins from the Folly.
There's a quirky access arrangement but don't let it put you off. I've never had a problem visiting on evenings or weekends and nor seemingly have the MTBers, horse riders, dog walkers, families building dens etc etc who are there every weekend. Just go discreetly and move on in the unlikely event of being challenged. Best not to have a lamp session though.