Good find Eric.
In recent years, some of the 'Cold War' bunkers, designed for use by local Government organisations in case of a nuclear strike against the UK, have been opened as tourist attractions. I find it quite amusing to see, in the middle of nowhere, a brown (tourist) road sign announcing 'Secret Nuclear Bunker' - someone missed the point, using the word 'Secret' !!!
Ah ha! Love your comments and I can say, having a Cold War bunker under part of my charge - the bloody thing would have been useless as the water table, when high, still floods through the living compartment. We once put a no swimming sign down there in keeping with our warped sense of humour.
Nice OP evanglider, I'll be watching this one.