HRH Charles's 17-Great Grandfather. Poss. Lady Diana's 16-Great Grandfather. HM Juan Carlos' 17-Great Grandfather. Philippe of Belgium's 17-Great Grandfather. Grand Duke Henri's 17-Great Grandfather. HM Margrethe II's 16-Great Grandfather. HM Beatrix's 13-Great Grandfather. HM Harald V's 16-Great Grandfather. Wm. von Bismarck's 12-Great Grandfather. `Red Baron' Richthofen's 13-Great Grandfather.