Correction to this article

PEDALLING to work each day, I spend most of the journey looking out for London's deadly, articulated “bendy buses”. The 60-foot beasts can happily scissor a cyclist while turning, so as I speed along High Holborn I have never given much of a second glance to the buildings that whizz past on each side.

That might be why I have never noticed anything unusual about 39 Furnival Street. A brick building in a row of offices, its black double-doors are unmarked and unremarkable. But if you stop for a moment and look up, you might reconsider that judgment. Above the entrance is an industrial-size cast-iron pulley—odd in a street of legal firms. Above that, curiouser still: a wide, gaping air vent of the sort that you might see at the top of a mine-shaft.

AFP

It's a secret building

What lies inside was once subject to the Official Secrets Act. But now this mysterious property is up for sale, and so I find myself with a few other journalists on the other side of the doors, signing consent forms and handing in my mobile phone (whose signal had mysteriously vanished as soon as I crossed the threshold). A lift takes us down 100 feet, deeper than the London Underground, which we can hear rumbling above us. A set of atom-bomb-proof doors are swung open and we step out into the secret of Furnival Street: the Kingsway tunnels, a miniature city beneath a city.

Dug in 1940 as London was blitzed by German bombers, the tunnels were designed as a air-raid shelter for up to 8,000 people, and as a possible last-ditch base for the government in the event of an invasion. They were never used as a shelter; instead, towards the end of the war they were taken over by the “Inter Services Research Bureau”, a shady outfit that was in fact a front for the research and development arm of MI6 (perhaps better known as Q branch in the James Bond novels).

After the war, the tunnels were passed to the Post Office and then to British Telecom, which hopes to sell the warren for £5m now that it is surplus to requirements. “I think it would make a great disco, personally,” says Ray Gapes, a former switch-maintenance engineer who came to work in the tunnels as an 18-year-old apprentice and is now showing us around.

During Ray's time underground in the 1970s, the tunnels were equipped with a restaurant, licensed bar and games room, including two snooker tables and a tank of tropical fish (piranhas, some say, though that might be James Bond fever taking hold). The fish-tank has gone but the bar is still there, complete with a garish orange and brown 1970s colour scheme and a few dirty dishes. Next door in the old restaurant, enough letters remain on the menu board to spell out the last dinner served down here: sausage, chips and peas.

It was a strange life: staff would telephone up to the surface for weather reports, to see if they should take an umbrella when they went out for a cigarette. Decorators did their best to make them feel at home: mirrored walls in the restaurant make it seem less cramped, and there are even “windows” looking out onto painted scenes of palm-fringed beaches and mountain lakes.

The tunnels—a mile of them in total, comprising two main drags and four smaller offshoots—have homely, superterranean-sounding names: South Street, Second Avenue and Tea Bar Alley. The illusion is only broken when you see behind the wood panelling the iron support structure, embossed with the initials of the London Passenger Transport Board, from whom parts of Tube tunnel were borrowed to build the complex.

The tunnels were still in secret use long after the Battle of Britain had given way to the Cold War. Deep under my bicycle route, technicians maintained the “hotline” between Eisenhower and Khrushchev, as well as a basic domestic network for Britain that would keep the country connected in the event of a major strike.

Richard Bamford, a senior technician on the site, describes how during the Cuban missile crisis the tunnels were locked down, fully manned, for a fortnight. Thanks to an artesian well and an independent generator (which powered old submarine chillers to keep the air breathable), staff could have lived down here for months.

The walls still ooze secrets. Mr Bamford declines to tell us where we are in relation to the outside world, in case a future buyer wants to keep things down here away from prying eyes (and shovels). And opposite a particularly Heath Robinson piece of machinery, complete with foot-long levers and dials like the engine room of the Titanic, I spot an old circuit diagram on the wall, mapping out each of Britain's national newspapers. Were they being bugged back then? Probably. The question on my mind as we make our way back to the surface is: in which tunnel are the eavesdroppers hiding now?





Correction: An earlier version of this article referred to the London Public Transport Board. The organisation is called the London Passenger Transport Board. This article was corrected on November 24th 2008.