HM George I's 9-Great Grandfather. Poss. HRE Charles VI's 12-Great Grandfather. PM Churchill's 17-Great Grandfather. Lady Diana's 18-Great Grandfather. PM Cameron's 19-Great Grandfather. HRH Albert II's 18-Great Grandfather. Louis XVII's 13-Great Grandfather. HM Umberto II's 16-Great Grandfather. `Red Baron' Richthofen's 14-Great Grandfather.