As if to back all this up, http://www.thames-search.com/binsey.html says of the church and well:

"It is part of the ancient priory of St Frideswide, a Mercian princess (died 735) who founded a nunnery in Oxford. Regardless of her decision to live a cloistered life, she was forced to flee the attentions of the persistent King Algar. Whilst Frideswide lived secretly and simply beside the Thames with a swineherd and his wife, Algar marched on Oxford with his army and the town was saved from devastation only by providence: Algar was suddenly struck blind, presumably as punishment.

The good Frideswide, though, felt sorry for Algar and prayed that his sight should be restored. In answer to her supplications a holy well sprang up (can a well spring up?) and Algar was healed by its magical water. St Frideswide built a church beside the well, which she dedicated to St Margaret of Antioch.

She probably felt some affinity with Margaret, the daughter of a pagan priest during the time of the Roman emperor Diocletian (245-313) who ordered the last great persecution of the Christians. Margaret also had to flee from the advances of an unwelcome suitor, the prefect Olybrius, who then denounced her as a Christian. She went through various tortures such as being swallowed by Satan in the guise of a dragon, and was finally beheaded."

So, an almost identical story, carried forward and repeated several hunred years later, from an old Pagan story? More like this, and I might start thinking I'm half right! ;o)

G x