North of Penzance, almost half way to the north Cornish coast, is the parish of St. Maderne,
situate vunder the craggie hills ... nere which is a well called Maderne Well, whose fame in former ages was great; for the supposed vertue of healing, which St. Maderne had therinto infused: And manie votaries made annale pilgrimages vinto it, as they doe euen at this daye vnto the well of St. Winifride, beyounde Chester, in Denbigeshire, wherunto thowsands doe yearly make resort.
It is a good guess that these wells had healing powers from Pagan times. The Christian saints, or at least their legends, may even have been invented or modified to Christianize the wells.
There are, of course, far too many such holy wells throughout England to itemize them all, and Maderne, although not specifically connected with Arthurian legend, is included here only as an example. Among powers sometimes connected with such wells is the quality that whichever partner, husband or wife, drinks the water soonest after the marriage ceremony will henceforth have predominance in married life.
At Alternun, Cornwall, is a “bowsening pool” wherein mad folk were formerly dowsed to restore their senses.