Imagine there’s a snowstorm. All the trains and Tubes stop running and everyone’s stranded.

The British Red Cross and insurance firm Aviva recreated that exact scenario last week in Hoxton Square as a training exercise for their new “community reserve volunteers” project.

“So many people around the country really do want to help,” said the charity’s Emma Spragg. “It’s a natural thing.

“But sometimes you don’t know how to help. So, this is a way of harnessing the kindness people have within them.”

During the simulation, 20 volunteers were briefed by emergency response leader Dara Leonard, who told the crowd they were there to “make the commuters feel as safe as possible”.

While half the group was busy transforming a warehouse into a rest centre, the other half was sent out to do some heavy lifting.

The volunteers quickly filled up the British Red Cross vehicles with food and big packs of bottled water.

Commuters slowly started to swarm into the fake rest centre – some cold, some anxious, some hungry and some outright impatient.

One man played the role of a foreigner who couldn’t speak English, which made it difficult for the volunteers to communicate with him.

A woman pretended to have a chronic illness and forgot to bring her medicine with her.

And, of course, you had the angry commuter who demanded to be put up in a five-star hotel.

Volunteers rushed to help out as fast as they could by handing out blankets, blowing up beds and dealing with any complaints or questions the commuters had.

The British Red Cross’s community reserve volunteers are ordinary people who have signed up to help whenever there’s an emergency near them. The goal of the simulation was to make sure those volunteers are actually prepared to cope with such a situation.

“We know people don’t have a huge amount of time and it’s difficult to commit regularly to something,” Emma, the charity’s director for London independent living and crisis response, told the Gazette.

“But our research shows over 90 per cent of people want to help if a disaster happens and over half of those wouldn’t know what to do. This project is to show there’s a way to sign up as a volunteer and just do it occasionally.”

Sean Dench, 40, was one of the first community reserve volunteers to be deployed to a gas leak emergency in Croydon last month.

“I got a text saying they need me,” he said. “By the end of the day I had this feeling that it was well worth going. You got a nice sense from actually helping out.

“You don’t need any skill sets. It’s literally just helping out, so there’s no reason not to do it.”

Emma added: “Our regular team with particular skills will already be on location. The community reserve volunteers are an invaluable extra pair of hands that’ll back up the team.”

Another volunteer who was also deployed that day – Ismahel Kolade Jimoh, 39 – said he participated in the simulation to make sure he’s more prepared next time. “I have a passion for helping people and now I finally found a way to do it,” he said.

Jessica Parker, 24, joined the simulation to find out what the community reserve volunteers were expected to do. “It felt very lifelike,” she said. “It was interesting to see how different groups of people worked together and how to take over various roles.”

The call for people to sign up comes after 2017 gave the British Red Cross one of its busiest years since the Second World War. The Manchester bombing, the Grenfell Tower fire and two terror attacks in London meant the charity helped 9,300 people across the UK.

Now it’s hoping to recruit 10,000 volunteers by November 2019. If you’re interested, they ask you to sign up at redcross.org.uk/reserves