Poss. HRH Charles's 14-Great Uncle. Lady Diana's 15-Great Grandfather. HM Juan Carlos' 16-Great Grandfather. Philippe of Belgium's 16-Great Grandfather. Grand Duke Henri's 16-Great Grandfather. HM Margrethe II's 16-Great Grandfather. HM Beatrix's 15-Great Grandfather. HM Constantine II's 15-Great Grandfather. HM Carl XVI Gustaf's 15-Great Grandfather. HM Harald V's 15-Great Grandfather.