HRH Charles's 15-Great Grandfather. PM Cameron's 17-Great Grandfather. HRH Albert II's 16-Great Grandfather. Louis XVII's 12-Great Grandfather. HM Juan Carlos' 15-Great Grandfather. Philippe of Belgium's 15-Great Grandfather. HM Manuel II's 14-Great Grandfather. Grand Duke Henri's 15-Great Grandfather. HM Margrethe II's 15-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. Ksr Wilhelm II's 13-Great Grandfather. HM Umberto II's 16-Great Grandfather. `Red Baron' Richthofen's 16-Great Grandfather.