Mehegan Family Genealogy Forum
I found some info in the Meighan family name. I'd heard a rumor about this but now it seems to have been confirmed. So here goes:
After the Battle of the Boyne, two brothers with the surname O'Meighan left for France. In order to compensate for the French language their name became 'Mehegan'. This is confirmed by French records of this surname. The name stayed in France for about a hundred years until the revolution, when they fled back to Ireland, some changing the name, some keeping it. Pretty turbulent origin of the family name, don't you think?
p.s. The two brothers became Baron Jacques de Mehegan and Compte Guillame de Mehegan (from James and William).