Agatha Christie's Seven Dials star Mia McKenna-Bruce talks "bundle of energy" character, The Beatles biopics, and beginnings with EastEnders and Tracy Beaker

This article first appeared in Radio Times magazine.

She stands at just five foot tall, but actor Mia McKenna-Bruce fills a room with her effervescent energy. It’s little wonder she was cast as Lady Eileen “Bundle” Brent (described by Christie as a “spirited, modern It Girl” and a “bright young thing”) in Netflix’s new adaptation of Agatha Christie’s novel The Seven Dials Mystery.

“It’s all in the name – she’s a bundle of energy, a force to be reckoned with,” McKenna-Bruce explains of her character. “She doesn’t take no for an answer but she probes with charm and a smile on her face.

“I’m completely shocked this story has only been adapted once before. Maybe it’s because we’re only now diving more into female-led narratives. Everyone falls in love with Bundle, she’s such a ray of sunshine.”

McKenna-Bruce leads a starry cast in the three-part thriller, which has been adapted by Broadchurch creator and former Doctor Who boss Chris Chibnall. The story, set in 1925, begins with a murder at a lavish country party. Unhappy with the police investigation into the death of her friend Gerry, Bundle decides to do some digging herself, which leads her into a murky world of espionage.

“It’s different to what we’ve seen before, but it still clings on to the things people love about Christie,” says McKenna-Bruce. “We’ve got the classic scene where all the suspects are in a room and Superintendent Battle is unpicking it all and revealing the killer. It’s got the dark side to keep you hooked constantly, but it’s set in the roaring 20s and has this young, fresh, glitzy vibe. Visually, it’s stunning and, for me, watching it made me want to jump into that world, despite all the death!”

Certainly, she’d be in good company if she did so. Bundle’s mother, Lady Caterham, is played by Helena Bonham Carter, while Martin Freeman is Superintendent Battle, and McKenna-Bruce says that both A-listers were a joy to work with. “Helena called us ‘the psychic sisters’ because we got on so well, and Martin was hilarious,” she says. “Whenever he forgets a line, he does a Chewbacca impression and it made me laugh every time. I was gone.”

Not that sharing a screen with big names is unusual for McKenna-Bruce. She is only 28, but she’s been acting since she was seven years old, and is currently playing Ringo Starr’s first wife Maureen in the first of four Beatles biopics directed by Sam Mendes and co-starring Saoirse Ronan, Barry Keoghan and Paul Mescal.

Her love of acting all began, she says, when she was just six and spellbound by the movie Titanic. “I couldn’t stop crying after I watched it,” she recalls. “So my mum got the director to ring and explain that it was a film, except that it wasn’t James Cameron on the phone, it was my grandad pretending. When he explained these people were acting, I was like, ‘I want to do that.’”

With many kids, that dream would be put on hold for a while – but within two years, McKenna-Bruce was in the West End performing in Billy Elliot, and landing roles on TV shows such as EastEnders, where she played Jack Branning’s daughter Penny. Other soap roles included The Bill and Doctors, as well as kids’ TV shows Tracy Beaker Returns and The Dumping Ground for eight years.

“They’re all incredible, fast-paced shows that gave me a springboard to switch in and out of character easily. It taught me not to cling onto a character or take home emotions,” she says. “You’ve only got a few minutes to do a scene, then you have to get out of that headspace and into the next. That’s been a real gift.”

But everything changed when she hit 20. Despite all that experience McKenna-Bruce decided to give up acting, unsure if she could make the transition to adult roles. “Up until then it was just a hobby. I didn’t know how to approach the industry as an adult,” she says. “The auditions I was doing didn’t feel fun any more, because I put so much pressure on myself, so I gave it up and went to Australia with my best friend where we had the time of our lives.”

But when she returned home, she felt a pull back towards acting and soon landed roles in Persuasion opposite Dakota Johnson and Richard E Grant, alongside her breakthrough lead role in How to Have Sex, a rite-of-passage teen film that won her the EE Rising Star Award at the Baftas in 2024.

Yet it’s only now that McKenna-Bruce is really breaking through to the mainstream. There’s Agatha Christie’s Seven Dials, of course, and the Beatles project, but she also takes the lead as Jane Andrews in The Lady, an upcoming ITV drama about the Duchess of York Sarah Ferguson’s lady-in-waiting, who killed her boyfriend. Two decades on from her early jobs, it may seem a slow trajectory but McKenna-Bruce says the timing for her big roles is perfect, coming as they do after marrying and having her baby son Leo two years ago. “Acting’s all I’ve ever known, although I don’t know if people realise how much experience I’ve got. I get ID-ed trying to buy Calpol for my son! I feel I might not have done Bundle justice in the past, in the way that I can now.

“For all that this story is fun and glitzy, there’s a lot of heart and grief behind it, and I don’t think younger Mia could have told the story in the same way. I have a lot more self-confidence now, I’m a mum and I’ve been through labour, so I’m really grateful that now is the time that I’m getting to tell this story.”

Looking ahead, the four Beatles films aren’t coming out until 2028, which means McKenna-Bruce has to keep tight-lipped about details for a long time yet. But she does acknowledge that her life may be about to change in a big way.

“It’s everything I could have dreamt of,” she says. “Everyone is pouring so much into it that I know it’s going to be pure magic. Sam Mendes has exceeded all my expectations and I pinch myself constantly that I’m a part of this masterpiece that’s going to take the world by storm. But I never go on a job and think, ‘This could be big’, or ‘This could lead to other things’. I just enjoy making it, and then I’m excited to see what we’ve created. I’m a water sign, so I go with the flow, and I just love what I do.”

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Agatha Christie's Seven Dials is on Netflix from 15 January.

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