HRH Charles's 17-Great Aunt. Poss. Lady Diana's 16-Great Grandmother. HM Juan Carlos' 16-Great Grandmother. Philippe of Belgium's 16-Great Grandmother. Grand Duke Henri's 16-Great Grandmother. HM Margrethe II's 16-Great Grandmother. HM Beatrix's 15-Great Grandmother. HM Carl XVI Gustaf's 16-Great Grandmother. HM Harald V's 15-Great Grandmother. Wm. von Bismarck's 11-Great Grandmother. `Red Baron' Richthofen's 13-Great Grandmother.