Poss. HRH Charles's 17-Great Uncle. Poss. Lady Diana's 13-Great Grandfather. HM Juan Carlos' 16-Great Uncle. Philippe of Belgium's 15-Great Grandfather. Grand Duke Henri's 14-Great Grandfather. HM Margrethe II's 16-Great Uncle. HM Beatrix's 13-Great Grandfather. HM Constantine II's 14-Great Grandfather. HM Carl XVI Gustaf's 14-Great Grandfather. Otto von Bismarck's 8-Great Grandfather. `Red Baron' Richthofen's 11-Great Grandfather. HRH Catharina-Amalia's 14-Great Grandfather.