WELCOME to Cold War City (population: 4). It covers 240 acres and has 60 miles of roads and its own railway station. It even includes a pub called the Rose and Crown.

The most underpopulated town in Britain is being put on the market. But there will be no estate agent’s blurb extolling the marvellous views of the town for sale: true, it has a Wiltshire address, but it is 120ft underground.

The subterranean complex that was built in the 1950s to house the Conservative prime minister Harold Macmillan’s cabinet and 4,000 civil servants in the event of a Soviet nuclear attack is being thrown open to commercial use. Just four maintenance men are left.

Property developers looking for the ultimate place to get away from it all need not apply. The site has a notional value of £5m but there is a catch. It is available only as part of a private finance initiative that involves investing in the military base on the surface above.

Already two uses are being considered: a massive data store for City firms or the biggest wine cellar in Europe. More outlandish ideas put forward include a nightclub for rave parties, a 1950s theme park or a reception centre for asylum seekers. The Ministry of Defence (MoD) has ruled out any suggestion of using it to store nuclear waste or providing open public access because of the dangers that still lurk below.

The bunker is in a former mine near Corsham in Wiltshire where stone was once excavated to provide the fascias for the fine houses of Bath, about eight miles away.

During the war the mine was a munitions dump and a factory for military aircraft engines. It was equipped with what was then the second largest telephone exchange in Britain and a BBC studio from where the prime minister could make broadcasts to what remained of the nation. The telephone directories were last updated in 1989, the year the Berlin Wall came down.

A system of underground power stations would have provided electricity to the 100,000 lamps that lit its streets and guided the way to a pub modelled on the Red Lion in Whitehall.

A spur line was built inside a tunnel on the main London to Bristol railway, linking it to the bunker. It was meant as an escape route for the royal family to flee London in the event of an attack.

Code-named Burlington, it was never used and as the timescale for a perceived Soviet nuclear onslaught shrank to the notorious four-minute warning of armageddon, the whole concept of evacuating the Queen and her government became obsolete.

The bunker’s very existence was meant to be top secret until it was decommissioned last year. The last cabinet records were removed a decade ago.

A visit there today involves walking into an opening in a hillside and taking a lift down to the bunker. The only sentry is a garden gnome outside one of the entrances. Inside, it is like stepping back 50 years.

Hundreds of swivel chairs delivered in 1959 are still unpacked. There are boxes of government-issue glass ashtrays, lavatory brushes and civil service tea sets.

Pictures of the Queen, Princess Margaret and Grace Kelly are pinned to the walls. The canteen has murals of British sporting scenes painted by Olga Lehmann who went on to design costumes for films such as The Guns of Navarone and Kidnapped.

“It was like a set from The Avengers,” said Nick McCamley, author of Secret Underground Cities, who lived locally and first discovered the existence of the site in the 1960s.

Wing Commander Steve Röver-Parks, who is in charge of the Defence Communication Services Agency, which employs 2,200 service and civilian staff above ground at the site, said: “The MoD is in discussion with several interested parties but nothing has been signed and sealed.

“The mine will be part of a private finance initiative. Whoever gets the buildings above ground will have the rights to the mine. Wine storage is under consideration.”

Wine should keep well at the bunker’s constant temperature once equipment to control the humidity is introduced. Vintners expect an explosion in the sale of fine wines next year when changes in pension regulations will enable people to invest their savings in claret.

Michael Lainas, managing director of Octavian, which stores 800,000 cases of wine in another former stone quarry — three miles from the bunker — which the company bought from the MoD, said: “It’s a nice idea going from a red scare to red wine. Our most valuable deposit is a 1666 bottle of sherry valued at £36,000 that once belonged to the tsar of Russia. But even I am not allowed down there with a corkscrew.”

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