|A real road sign, in the County of Essex, UK|
The road sign is real and the bunker is real. In the 1960s, at the height of the Cold War, several emergency regional seats of government were built in Britain and this was one of them. It is now a tourist attraction, of course - even our government would not be so stupid as to pin-point it's location. I think.
It always makes me smile when I drive past this sign which is not far from where I live. I am still not absolutely certain that the joke was obvious to whoever put the sign there. (Epping Forest District Council I believe).
As an afterthought, I wonder.....if there had been a nuclear war how would they choose who gets a place in the bunker? What's that you say? Politicians? Surely not!