It happened again with the conflict in the Middle East last month. “I got two enquiries for nuclear bunkers the week the conflict started,” he said. 

Some have been after residential protection for longer. In 2017 Weldon was asked to build a bunker in leafy and well-heeled Wimbledon. 

“We designed and installed a shelter with its own generation power supply and water unit,” he says. 

“We did that one and then off the back of that we have done some more, some internationally as well. The builder who was doing the fit out with us had struggled to find anyone who could fill the brief. We could fill that specification.”

Like Hardman, he says there has been a ‘flurry’ of interest in both over and underground bunkers since the invasion of Ukraine.

“Some [clients] are trying to protect from a very close explosion but some of the units are a little bit more rural. So they are looking at they may be on the outskirts of a blast radius and be there for up to four weeks. Just sit it out knowing they have breathable air,” he says. 

The units are kitted out with safe drinking water, dried food and things you need to sustain life. 

“We have done about half a dozen since Ukraine,” says Weldon. “It is the nature of the business.”

But not all clients are looking to build a full nuclear bunker. Instead some are investing in equipment such as NBC (nuclear, biological and chemical) filter systems. 

From safe rooms to bunkers with swimming pools

Others are looking at converting existing rooms in their homes into panic rooms that do not offer the full protection of a bunker, but provide more security than the rest of the house. 

“Initially it was just about the Ukraine war but as it has gone on people have looked at the bigger picture and are uneasy,” Weldon adds. 

“The wealthy are definitely worried because what I have found is where I have just been putting a safe room in a big new renovation, now the mindset is should we go to the next level, to add in a water filtration system.

“When doing a renovation, panic rooms are now part of the build as well as a swimming pool, new kitchen etc.”

The fitting out of a safety room usually takes about six weeks, while installing and kitting out a full bunker takes around three months.

Converting a cellar or basement is another option, says Valdas Macys, head of international sales at Castellex – maker of NBC air systems. “They are not as sophisticated as a purpose built shelter but will increase your chance of survival. The most important thing is to survive the blast and the shock after.” 

There are also other factors to consider. 

“The process of designing a nuclear bunker is not easy,” says Hardman. “There is a planning process to go through and that can be difficult. The planning departments can’t seem to get a grip on a nuclear bunker in their planning policy.”

Engineering considerations and technical issues around building controls also need to be looked at.  It is also not cheap. Prices for panic rooms to bunkers typically range from £250,000 to £1.5m.