In reply to ben b:
That's an excellent point, ben b.
Clearly it can not be a UK winter route if it is recorded outside the UK and outside the true winter of Dec 22 - March 21 (no doubt some pedantic almanacist will drop a note about more precise dates, but I can't be bothered to toss the argue.).
Which means that it would be impossible to climb Central Icefall on Craig y Rhaedr in Snowdonia on March 31st, wouldn't it? (In the UK, but not in winter....)
But the impossible actually happened.