Trigger Point: Vicky McClure on the return of ITV thriller with Leeds Happy Valley star Mark Stanley

Washington, played by Line Of Duty’s Vicky McClure, is an ‘expo’, a member of the Metropolitan Police bomb disposal squad. ITV’s tense drama, Trigger Point, follows Lana and her team of experts as they work to defuse bomb threats and track down shady perpetrators.

Almost every episode of the first series was punctuated by nail-biting moments, near-misses and unexpected, devastating deaths. For Lana, many of those were personal. Her younger brother was killed in one attack, a close colleague in another. She returns after a six-month hiatus from work to get her head together – or that was the idea, anyway. Season two promises more of the same breathless intensity.

“Lana can’t catch a break!” confirms McClure. While it was great to step back into the part of brave, trauma-scarred Lana, “there was a heavy load to come back with because of what happened to her in series one”, she says.

“It was great to make sure we took that on board and honoured all of those awful scenarios and losses that she had,” she continues. “It is non-stop, it is edge-of-your-seat, it is entertaining television.”

But for the real-life expos that work, often surreptitiously, often unacknowledged, to keep us safe – the individuals who run full speed into the dangerous places people are running from – this is their day-to-day reality.

McClure and her on-screen team – Danny played by Suspicion’s Eric Shango and Hassan Rahim played by Blue Lights’ Nabil Elouahabi – spent time with bomb disposal experts ahead of filming to learn about their perilous work.

“We do work very closely with the advisers because we want to get the technical details right,” explains executive producer Jed Mercurio, the creative behind numerous hit dramas including Bodyguard, Bodies and Line Of Duty. “And also it’s really important to pay tribute to the work they do.

“They’re incredibly heroic. What they do is so courageous, but when you meet these people who are doing this incredibly dangerous job, they’re all so down to earth, they’re so humble. And it’s just so amazing that they’re like that. So we love working with the expos.”

“The expos haven’t got a clue what they’re walking towards,” says 40-year-old McClure. “They don’t know who’s behind it, they don’t know how they’ve put it together, what the tripwire might be, if there is one. There’s so many different variables when it comes to the devices. Some can be very complex and some can be very simple, but they both have the same effect.”

McClure is often seen in a huge, astronaut-esque bomb suit that expos wear to protect themselves. The suits weigh some 90 pounds.

“There was a choice this season where costume said, ‘look, we could make something [lighter] for you’, because it is so incredibly heavy to the point where it’s probably about the same that I weigh,” McClure relates.

“I said no because I just feel like I’m an actor, they shout ‘cut’ and I can take the helmet off – bless Eric, he’s always there on hand because I physically wouldn’t be able to do it alone – but I think it’s important for us to show the real deal. I remember on that day where you see me trying to get the mirror round the bend in the gate, I couldn’t lift my arm, it was so tough.

“And it just always reminds me how much respect I have for expos, not just for the fact that they walk towards potential death and danger every time they step out, but just the equipment and all that kind of stuff. When we did the first series, we spoke a lot about that kind of gear that wasn’t as accessible to women, because most of those kinds of uniforms are made typically for men.”

An unexpected consequence of the show was the “huge influx of people that applied to become expos, females as well, which is quite rare”, McClure says. “That was what attracted me to the role initially, because I was just like, ‘what is an expo?’ I’d never heard of the word. I knew about bomb disposal, it’s a whole world that was sort of untouched. And so it exposed something to people that has attracted people to want to do it, which is no bad thing.”

Within the overcrowded crime genre, Trigger Point hit a chord with viewers – the first series averaged over 9.5 million viewers an episode. Trigger Point reunites Mercurio and McClure who worked together on Line Of Duty, where McClure played Detective Inspector Kate Fleming.

“When a show goes out on TV, you never know what’s going to happen,” says Mercurio. “And so the fact that so many people came to the show and stuck with it was incredibly rewarding. We were absolutely thrilled by the response.”

That success added weight when it came to making a second season. “You have to find that balance between breaking new ground and delivering on expectations”, explains Mercurio, 58.

The tense action is grounded by the very human, very complicated relationships between the characters. There’s a new cop on the scene, DS Helen Morgan, played by Outlander’s Natalie Simpson, and with her arrival a love triangle between Lana, her ex-boyfriend DI Thom Youngblood (played by Happy Valley’s Mark Stanley) and his new love interest, Helen.

There is a part fraught, part humorous scene where Lana and Thom share a passionate moment – while his foot is on a trigger that will set off an explosive if he moves.

“I think if you work as an expo or in the army or in any kind of job that has that kind of danger attached to it, there is a certain gallows humour that the expos have talked to me about,” says McClure. “Being cool about things, not ‘ah there’s a bomb!’, that’s her job.”

Trigger Point returns to ITV1 on Sunday January 28.