I have finally solved the mystery of the standing stones. I had guessed that
they were not an ancient monument as I had never heard of them and goggling
various historical or archaeological pages found no trace of them. So I eventually
asked a friend whose husband is a keen hillwalker and he reckons they were
erected in the last ten years or so. I am not sure why they, and a nearby
'Dolmen' were put up but it's possibly because they are close to the course of the
Poc Fada, an annual competition where hurling players hit a 'poc' or ball
across the mountain with a hurly stick.
Whatever the reason, they make for very interesting photographs!