As /u/Aurevir has said, Queen's Order 2 was essentially the British plan for mobilization in the event that the Cold War turned hot. It called up the Territorial Army and provided some extra powers to the military to ensure full mobilization.

I say "was" because it was replaced with the Reserve Forces Act 1996.

I had never heard of it previously, and some searching yielded little reference to the term. What little I did find seems to indicate that it refers to calling up the Territorial Army, which is the UK's army reserve force, which can be activated in event of war, hence the mention of German airports- a lot of British soldiers would have to be flown over quickly to make a difference in a showdown with the Soviets.
If it does indeed exist, it's quite obscure, so take this all with a grain of salt.

Sorry for the mispels, I am currently travelling and can't edit the post with my phone :.