It is indeed an Unnamed Reserve. My local still has half the box left, but no other Opux X unfortunately. The inside of the lid has 'Sin Nombre' or 'Without a Name' written stylistically, I really liked it haha. The cellophane bears the print 'ProducXion 2016'.Not sure that's an opus - I've never seen one without the (in)famous X band, except special one-offs people got from the factory. Could it be the Unnamed Reserve? If so, you are a lucky man as they're very hard to find.
DB was 11 and the tins were 12