HRH Charles's 17-Great Grandfather. Lady Diana's 18-Great Grandfather. HM Juan Carlos' 18-Great Grandfather. Philippe of Belgium's 18-Great Grandfather. Grand Duke Henri's 18-Great Grandfather. HM Margrethe II's 16-Great Grandfather. HM Beatrix's 14-Great Grandfather. HM Constantine II's 15-Great Grandfather. HM Carl XVI Gustaf's 15-Great Grandfather. Ksr Wilhelm II's 15-Great Grandfather. Wm. von Bismarck's 11-Great Grandfather. `Red Baron' Richthofen's 13-Great Grandfather.