Sorry, I was a bit slow off the mark there. I've not yet visited this site, but I nearly did the week before last (ran out of time). I'd be interested to know what the access is like (in boring lengthy detail if possible).
As a part of my quest - I hve come across this new wrinkle.
I understand Meini Meibion Arthur is located below the Preseli Hills near Cwm Garw farm. Are these standing stones the same as Cerrig Meibion Arthur by another name? Cwm Garw Farm doesn't seem very close to Foel Cwmcerwyn - which is where Cerrig Meibion Arthur is located according to my information.