hi maureen,
The name 'Guinevre' is one theory but I was informed the 'son of jenifer' theory is more likly.I was told back in the 15th-16th centry peoples name was derived from 'son of' ie son of blacksmith now known as smith and in Cornwall about this time I was told the name Enifer/Enefer was starting to appear. I hope this helps
P.S Don't take this as gospel I carn't be sure of the source
Peter Enefer