HRH Charles's 9-Great Grandmother. PM Cameron's 11-Great Grandmother. HM Juan Carlos' 9-Great Grandmother. Philippe of Belgium's 10-Great Grandmother. HM Manuel II's 9-Great Grandmother. Grand Duke Henri's 10-Great Grandmother. HM Margrethe II's 9-Great Grandmother. HM Beatrix's 9-Great Grandmother. HM Constantine II's 9-Great Grandmother. HM Carl XVI Gustaf's 9-Great Grandmother. HM Harald V's 9-Great Grandmother. Ksr Wilhelm II's 7-Great Grandmother. Boris Johnson's 11-Great Grandmother.