Following the German invasion of Poland, a lot of polish soldiers fled to the UK and fought with the British forces. I'd like to see England and Poland having some sort of relationship there for a while. It wouldn't be especially fluffy, considering the setting, but you don't need to get to the Yalta conference and and the Western Betrayal if you don't want to!

It doesn't have to be romantic either, friendship is perfectly cool too!

bonus: they both do some fighting, of course, and Poland either is a pilot (many of the pilots in the Battle of Britain where Poles), or is still active in the Armia Krajowa (the resitance movement)