Seems all families are full of these stories, passed on as absolute fact, probably getting more and more embroidered as time goes by.
My mother in law always claimed that the surname De Boo had been changed from De Beaux only a couple of generations back. Well - back into the 1700's it is still De Boo or Debo or other such spellings!
My father was always told that his grandmother was nee Archer and that her family was linked to a Lord and Lady Archer. Sorry, her maiden name was Kemp, though actually her mother's maiden name was Archer, but sorry, again, no sign of any dignatries around!