HM George I's 7-Great Grandfather. HRE Charles VI's 8-Great Grandfather. Lady Diana's 16-Great Grandfather. PM Cameron's 16-Great Grandfather. HRH Albert II's 16-Great Grandfather. HM Margrethe II's 14-Great Grandfather. Wm. von Bismarck's 12-Great Grandfather. Boris Johnson's 16-Great Grandfather. `Red Baron' Richthofen's 13-Great Grandfather.