If the balloon – or rather the mushroom cloud – had gone up during the 1970s or 1980s, this is where the last people alive in Ipswich could be watching the devastation.

But they probably wouldn’t have been around for long after a nuclear attack because the town’s bunker under the police station and former Crown Court would only have offered very limited protection.

The bunker has entrances from both the police station and the court, in case one was blocked in the blast, but it is only about 12 feet below street level.

And it is accessed through apparently normal doors – there is no sign of the thick lead-lined doors that feature in films or TV dramas about a nuclear conflict.

We visited the bunker with Ipswich council leader David Ellesmere, the borough took over the building at the end of last month after the police moved a short distance to their new station in Museum Street.

The bunker itself has a number of rooms, which all had different uses during the day-to-day operation of the police station.

However at times of civil emergency it could be a control centre for the whole of Suffolk – and still has maps on the wall showing the river system and details of the road and rail network across East Anglia.

The bunker includes several rooms, including a small kitchen, toilets, and plant rooms. It is not clear what was in the plant room, but it seems likely to have included an independent generator.

There was a stock of iodine tablets available which would be taken to stave off the worst effects of radiation sickness.

However Mr Ellesmere doubted whether those in the bunker would have a long-term future.

He said: “I remember the TV drama Threads from the 1980s which dealt with the effects of a nuclear attack on the city of Sheffield.

“There was one scene about a month after the attack when the army reached the bunker that had been the nerve centre for the city.

“They found it was intact, but everyone inside was dead from radiation poisoning – I’m sure that is what would have happened here.

“There were smaller bunkers in the countryside, and all they were for was for someone to send details of what had happened there – there was no expectation they would survive. I suspect it was the same here.”