Katherine Kelly reveals the “most terrifying thing” in her “rip-roaring” new thriller In Flight

In any given year, the only similarity shared by the characters that Kelly plays is that they are completely different from each other. In every role, blue-collar or upper-crust, she’s thoroughly convincing; as credible downtrodden as she is haughty. Impossible to typecast, perhaps Kelly’s neatest trick is that she transcends class.

“That is a big compliment,” she says, a little thrown. “It’s one of the biggest barriers on and off-screen and I made a real conscious effort, very early in my career, to prove that I can play both. I’m a working-class girl from Yorkshire, but I went to Rada and didn’t do anything in my own accent until the last play I did.

"That’s why it was so important to me to play Lady Mae in Mr Selfridge after Corrie, because she was right at the top of the food chain in that show. Because of that, it’s never been an issue – although sometimes I do have to remind people that I am actually happier in a tracksuit than I am in a suit.”

Class is on Kelly’s mind a lot these days. With her partner, award-winning writer Tony Pitts, she has established her own production company Make Me Films, to spot and nurture working-class talent.

Later, Pitts will join us and tell me that it’s harder now for working-class kids to get into the arts than it was when he started out more than 40 years ago. Kelly agrees, “Getting your foot in the door is harder than ever and I find it really deeply upsetting that all that talent out there that is being ignored.”

And so Kelly and Pitts are working with Arts Emergency, the mentoring charity and support network co-founded by the comedian Josie Long, to establish training schemes and outreach work.

At a time when provision of arts subjects in state schools have been slashed, Kelly says “there are kids out there who are artistic but not from privileged backgrounds, who don’t think they have permission to get involved with the arts or creative industries”. As Pitts adds, “unless it’s put in front of you, you don’t even know it exists. If you can’t see it, you can’t be it”.

Kelly’s latest role in Channel 4’s crime thriller, In Flight, is closer to Corrie’s Becky than to Mr Selfridge’s Lady Mae. Jo Conran, working as airline cabin crew, is “an everywoman” whose life is turned into “a living nightmare, frankly” when her son is imprisoned in Bulgaria and she is blackmailed into drug smuggling by some Very Bad Men on pain of his death.

It’s clearly Kelly’s show and she is in almost every scene of the six-part drama. In a four-month shoot, from last November to this February, she had barely a day off.

“Jo wakes up every morning and she doesn’t know if her son’s dead or alive. She then has to put her front-of-house face on and smile her way through the day. To be that polished and then to feel that edgy and raw was so appealing to me,” Kelly explains. “As it goes on, she becomes more adept at what she’s doing, but there’s never a point where you feel like she’s on top, like she’s in control of what’s happening. She’s constantly failing upwards. She messes it up, then she fixes it. She messes it up and then she fixes it.”

For Kelly, the scariest aspect of this “rip-roaring thriller” is that “Jo’s not just fighting individuals, she’s fighting systems; the underworld system and the legal system in Bulgaria. Being at the whim of a system is the most terrifying thing.” As in Mr Bates vs the Post Office, where she played Angela van den Bogerd, a senior executive at the postal company? “Exactly. Terrifying.”

In Flight is also a story about the lengths to which a mother will go in order to protect her child. “She’s doing all of this to save her son’s life. I think she gets to a point, with the guilt and the knowledge of what she’s doing, that she’d rather not live. But she wants her son to live so she keeps doing it.”

Coincidentally, the same man cast her in both Coronation Street and her latest drama. In 2006, Tony Wood was Corrie’s executive producer. Today, he is CEO of Buccaneer Media, makers of In Flight, as well as Paramount+’s The Crow Girl, another project in which Kelly stars.

“I was in my final week in the Corrie job when I cast her from her audition tape,” Wood explains. “On it, she was adding a layer of detail and emotional range to the character that nobody else who auditioned got anywhere near. I was gutted I didn’t get to actually meet her then – until The Crow Girl, in fact.

“The more you ask Kate to do, the more she’ll stretch to. She gets on with it all, she asks all the right questions, and she’s very dynamic. She goes so far in the emotional rendition of the part.”

Wood’s praise goes some way to explain why Kelly is also an executive producer on In Flight. In short, she’s earned it. “I’m a very all-or-nothing person, so if I’m doing the job, I’m 100 per cent,” she says. “So I was delighted to be asked to be an exec producer and I’m so proud of this show that I was very pleased to put my name to it in another way, as well as first billing.” Kelly hesitates, squirming. “But I don’t want to sound arrogant. That doesn’t sound arrogant, does it?”

A tense and claustrophobic six-part thriller shown over two weeks, In Flight’s skies may be wide as Jo jets between London, Istanbul and Thailand – all filmed, inventively, in Belfast, in fact – but it’s often uncomfortably intimate and an incredibly stressful watch.

Do parts like Jo stay with Kelly? “I’m not a very retrospective person. I’m very forward-moving and if my thoughts rest, it’s always on the future,” Kelly says. “I’ve never taken it home with me or let it bleed into real life. I’ve always been very good at switching off the emotions. Most of the time, I’m just so grateful that that’s not happening to me.”

This must come in especially handy on dark dramas like The Crow Girl and the devastating The Long Shadow, in which she played Emily Jackson, the second victim of the serial killer, Peter Sutcliffe. “The Crow Girl is part of a trilogy and we’re making the next one this winter and the second book is so much bleaker than the first – I found that book really hard to pick up,” she says.

“The company that had the option before gave up because they couldn’t see how you could make it for television. So I’m really proud that we didn’t just make it, but that Milly Thomas’s scripts were so good, it got great viewing figures and it was reviewed so brilliantly.”

If nothing else, Kelly has no time to stew as a divorced working mum with two daughters, so when I ask how she juggles her priorities, her eyes narrow. “I hope you ask dads questions like this…” she says, pointedly.

“I was always quite picky but I’ve got a lot pickier. When I first came to this business, so much was filmed in London. Now, there’s so much made in mainland Europe or other UK cities – The Crow Girl was Bristol, In Flight was Belfast – that these days it means being away from home for work. And for me to be away from my kids, I’ve got to really want to do it.”

For the first five years after drama school, Kelly did nothing but theatre and, having not done any for a while, she misses it. “My heart is theatre and hopefully next year,” she says, wistfully. But having young children makes working in theatre particularly challenging so, in the meantime, she’ll continue to defy typecasting on screens of varying sizes.

Fundamentally, Kelly is a grafter. “You have to earn it. You have to prove that you can do it and that people believe you are versatile enough to play all these different characters. It’s the biggest compliment to me that I get entrusted with these characters. You’re only as good as your last job, so you have to make every job count.”

The latest issue of Radio Times is out now – subscribe here.

Check out more of our Drama coverage or visit our TV Guide and Streaming Guide to find out what's on. For more TV recommendations and reviews, listen to The Radio Times Podcast.