Larry Clopper is very right, I think, about Mahound, and one connection that is
very strong involves the crusaders. Then, Thomas Becket's mother was reputedly
a saracen princess who helped his father escape from prison, whereupon she
followed him to London. She is said to have known but one word ("Becket"),
which led her to her husband-to-be. There is a nice panel of painted glass in
St. Michael-le-Belfrey, York, which shows her being baptised, obviously a
convert from Mahound worship.
Also right about Jews in England. No real live Jews that I know about after
their expulsion, which was a pretty bloody affair.