In my opinion, one of the most beautifull autumn crocuses, with huge, deep blue purple flowers from September/October, almost 10cm's across in full sunshine when open. 

Beware of some offerings of this plant in lists, it is often not 'oxonian', but simply the "normal" form of speciosus, with much smaller flowers. This however, is true stock, which has flowered regularly with me for several years now.