Poss. Lady Diana's 18-Great Aunt. HM Juan Carlos' 17-Great Grandmother. Philippe of Belgium's 17-Great Grandmother. Grand Duke Henri's 17-Great Grandmother. HM Margrethe II's 17-Great Grandmother. HM Beatrix's 17-Great Grandmother. HM Harald V's 16-Great Grandmother. `Red Baron' Richthofen's 15-Great Grandmother.