Thank you for your comment Bloodbeard (pirate?). I thought after I asked this question that it was probably spurious; wells are ususally as old as the land itself and it is only when communities discover them and use them that they attain a history. It seems to be a given that wells named after saints were probably in use and revered by pre-Christian communities and dedicating them to a 'saint' was the early Christian church's way of eliminating pagan beliefs.