Charles, Prince of Wales was a grandchild of at least one wife of a king.
Charles , Prince of Wales ( Charles Philip Arthur George ; born 14 November 1948 ) is the eldest child and heir apparent of Queen Elizabeth II . Margaret Hanmer ( c. 1370 -- c. 1420 ) , sometimes known by her Welsh name of Marred ferch Dafydd , was the wife of Owain Glyndŵr .