HRH Charles's 19-Great Grandfather. PM Churchill's 17-Great Grandfather. Lady Diana's 19-Great Grandfather. HRH Albert II's 18-Great Grandfather. HM Juan Carlos' 17-Great Grandfather. Philippe of Belgium's 17-Great Grandfather. HM Manuel II's 16-Great Grandfather. Ksr Wilhelm II's 16-Great Grandfather. HM Umberto II's 16-Great Grandfather.