So the holder of the copyright, HM The Queen, has appointed the Director of OPSI to administer the copyright. Since OPSI administer the copyright THEY determine when and how it will be enforced. We have a statement in an email from one of their staff that they consider all Crown copyright in published materials to lapse at the same time worldwide as it would in the UK, ie 50 years from publication.
Given the importance of clear copyright rules on wikipedia, this statement has exactly a 0 legal value. What we should get is at least a non-exclusive license granted to wikipedia.
Also, I thought we were not only talking about copyright of uk public servants, but about copyright of uk authors at large before 1954... ?