Government would have limped on after an atomic war from places like Kelvedon Hatch Secret Nuclear Bunker and RAF Hack Green (for the UK). Valuable members of the public, the armed forces and some critical industries would also be protected to a degree, but most would have perished! No doubt some places would survive "Poland is 'toast'!" and in time form small principality and city states like this S.E. Polish one, The Republic of Mount Tarnica, which I made on another wiki.