HM George I's 8-Great Grandmother. HRE Charles VI's 10-Great Grandmother. PM Churchill's 16-Great Grandmother. Lady Diana's 17-Great Grandmother. PM Cameron's 18-Great Grandmother. HRH Albert II's 17-Great Grandmother. HM Margrethe II's 15-Great Grandmother. `Red Baron' Richthofen's 13-Great Grandmother.