I lived in Kelly Bray in the early seventies and I never heard that particular legend about King Arthur. He was rumoured to have been conceived at Tintagel, which is on the other side of Bodmin Moor. You can see his Stone at Camelford. I used to practise my football skills on a disused mine top, where the uneven bounce forced me to pay attention!
I wonder which cemetery you are talking about. Is it that one on Liskeard Road about half a mile from the centre of Callington?