HM George I's 9-Great Grandfather. U.S. President [McKINLEY]'s 15-Great Grandfather. PM Churchill's 15-Great Grandfather. Lady Diana's 17-Great Grandfather. PM Cameron's 18-Great Grandfather. HRH Albert II's 17-Great Grandfather. Louis XVII's 13-Great Grandfather. Gen. Pierpont Hamilton's 14-Great Grandfather. Poss. Jamie's 17-Great Grandfather.