I'm not sure if anyone has answered your question Jane and I can't be bothered to go through the thread!
One certainly is G-y-F (Carmarthenshire-1-1977) but I don't think the other one is. I thought it might be Carreg Coetan Arthur but I can't really tell.
I like the pictures of John Bennett (see http://www.jbgallery.co.uk/page4.html) - we have Pentre Ifan in our lounge.
Cheers
Paul