Nightsleeper: Could a cyber hack derail a train in real life?

Cole and Roach’s characters have to work together to stop the impending train wreck, with Joe on the train trying to disable the hacking device placed in the control room while Abby and her team frantically try to work out who is behind the “hack-jack” from the National Cyber Security Centre.

Strangers until the crisis hits, the pair communicate on an unreliable satellite phone as they desperately try to save the lives of those on board.

The tension is palpable but it’s frequently undercut by the drama’s very British sensibility, namely dark humour.

“I thought it was just a really fun, proper, authentic British drama,” Cole says. “Some of it’s a bit silly… some of my lines… you could read them, in a way, cheesy and I was like, OK, this is going to be fun.”

“I did Skins back in the day, and there was some absolute cheese on toast with a slice of halloumi in that. And I remember enjoying the challenge of saying some of the more ridiculous lines and pulling them off.

“I’ve been on many sets where actors [say]: ‘I can’t say that. We’ve got to change it.’ And often it does get changed. I actually like the challenge of trying to pull off the more crazy lines.”

Roach adds: “As British people that’s what we do, isn’t it? When we’re tested under pressure it’s to find those moments of humour… that’s what makes us human.”

Leather concurs: “It’s how we respond to a crisis, there’s got to be a lot of gallows humour there – if we don’t have that and it’s cod-American, it’s not going to work. It has to be the British way. And we love to moan about trains!”

He adds: “I’ve always liked Hollywood thrillers, the guilty pleasure, the escapism of it. It’s melding the two very different styles together (US thriller with British drama).”