At Madron beyond Penzance is a very ancient and famous holy well and holy tree. There is also an ancient chapel which, though rebuilt, could be the oldest in Britain going back as far as the 6C, if not earlier. Inside it is a place for immersion and also the ‘bed’ (grave) of St Madern. The sick person was immersed in the waters and then laid on the bed in order to be healed. It may be that at one time there was an altar over where the water flowed in, as in other well-chapels. You cannot get nearer the ancient British church than at Madron.
It wll not come as a surprise that at such a remarkable site is taken to belong to some else: for the pagans, he is now a she, Modren, a Celtic mother goddess from Wales.