Peter Hennessy begins the third volume of his splendid history of postwar Britain with a vivid description of the secret bunker complex, created in the late 1950s and early 1960s near his boyhood home in the Cotswolds. Code-named STOCKWELL, it occupied 240 acres and included 60 miles of tunnels dug 90 feet below ground. This ‘troglodytic mini-Whitehall’, as he terms it, was built to accommodate four thousand senior ministers and officials in the event of a nuclear attack, and it was equipped with every conceivable post-Armageddon provision, right down to the appurtenances of salvation, crosses and candlesticks. Decommissioned in 1991, it still contained relics from its previous state when Hennessy inspected it fifteen years later: chipped white crockery in the canteen, maps and Russian dictionaries in the library, telephone books in the communications centre as well as, bizarrely, a copy of The Encyclopaedia of Sexual Behaviour. He also noticed a doom-laden graffito scratched on the limestone walls: ‘STUCK HERE 4 ETERNITY’. Hennessy was permitted to take away a tea towel as a souvenir. It was emblazoned with the letters ER, dated 1960 and marked TETW, which presumably signified ‘tea towel’ but which he was tempted to interpret as shorthand for ‘The End of The World’.

It was an understandable inference in view of the fact that this subterranean bolthole was completed just when the Cold War was threatening to turn white hot. At no other time since the end of the Second World War