HRH Charles's 17-Great Uncle. Lady Diana's 18-Great Uncle. HM Juan Carlos' 18-Great Uncle. Philippe of Belgium's 18-Great Uncle. Grand Duke Henri's 18-Great Uncle. HM Margrethe II's 16-Great Uncle. HM Beatrix's 14-Great Grandfather. Wm. von Bismarck's 11-Great Grandfather. `Red Baron' Richthofen's 12-Great Grandfather.