Nightsleeper's ALEX ROACH on how her career nearly hit the buffers

Just before I’m due to meet Alexandra Roach I get a call from her publicist. The star of the BBC’s shiny autumn series Nightsleeper, which is about passengers trapped on a runaway train, is… stuck on a train. ‘I can’t believe the irony of this,’ she apologises.

It’s no big drama: we simply meet in London’s Soho a little later than planned. But Nightsleeper is a big drama. If you missed its start, the gist is this: a Glasgow to London sleeper train is ‘hackjacked’ by a mysterious cybercriminal called The Driver and hurtling towards the capital like a missile. The terrified passengers make a beeline for the first-class minibar (exactly what Roach and I would do, we agree) as they rocket to their final destination.

Roach plays Abby, acting technical director of the National Cyber Security Centre, desperately trying to talk passenger and off-duty police officer Joe (Joe Cole) through saving the train over the phone (the hackers have disabled every device on board apart from a satellite phone belonging to an oil-rig worker) while trying to puzzle it out herself. It’s fun: a bit 24, with mile-a-minute twists and spills (in one grisly scene the train rolls over a hapless passenger who has fallen on to the tracks with a wince-inducing squelch), and part Murder on the Orient Express 2.0, an all-aboard whodunnit for the information age.

It hasn’t put her off public transport for life, says Roach, 37, her blue eyes twinkling under a bob. ‘But for the others in the cast it was six months on a tiny carriage, quite claustrophobic, and now they say they never want to go on a train again.’

Roach grew up in the small mining town of Ammanford, Carmarthenshire, in the shadow of the Black Mountain. It was a ‘very close-knit community, lots of chapelgoers’ where ‘nearly 80 per cent of people speak Welsh’. Her parents owned a pub, and it was an all-singing, all-dancing kind of childhood (her earliest memory is being on top of the pool table).

She has been acting professionally since the age of 11, when she was cast as Elin Owen in Pobol y Cwm, the long-running ‘Welsh-speaking EastEnders’ (they’d shoot at weekends and she’d go to school in Swansea during the week). Her storylines included a teenage pregnancy, a furore about being caught smoking at school and trying to pursue an affair with a vicar. She was even named best child actor in a soap at the annual Children in Entertainment Awards in 2003 and secured small parts in Harry Potter and the Philosopher’s Stone and the Hugh Grant movie About a Boy.

She moved to Camden in North London to train at Rada aged 18, where she became best pals with Susan Wokoma (star of BBC’s Cheaters). But she found London tough. ‘I felt lonely,’ she says. ‘Even though there are people everywhere.’ While at drama school, she was rebuffed from one audition the minute she opened her mouth to tell the casting director she was from ‘Swansea, Wales.’ ‘Oh no, she’s not right,’ he said. ‘[Having a Welsh accent] was a thing,’ says Roach. ‘That’s what’s celebrated now, what makes you different, but it wasn’t back then.’

Her first big role was as a young Margaret Thatcher in Phyllida Lloyd’s 2011 biopic The Iron Lady. ‘[For the audition] I went to the hairdresser, got curls in my hair like my gran would have. I went to a charity shop and found a blue suit,’ she says. ‘At the audition I was the only one dressed as Thatcher. Everyone else was in trainers and jeans.’ After spending a weekend trying to forget about the whole thing at Bestival on the Isle of Wight, she was surprised and delighted to learn she’d got the part. ‘I’ve still got the teeth,’ she says. ‘They’re in a box in the loft.’

The role meant working with Meryl Streep, who played Thatcher later in her career. Roach remembers arriving at Pinewood Studios to find the Oscar-winner and Jim Broadbent (who played Thatcher’s husband Denis) rehearsing a scene to The King and I’s ‘Shall We Dance?’. ‘Then the music stopped and Meryl turned. She was, like, “Aaaalex!” [she puts on a big American drawl and throws her hands wide], and she came striding across this big studio to wrap me in the most amazing hug. And it was, like, “Wow, how is this my life?”’

There have been moments when she felt that ‘maybe I shouldn’t do this, maybe I haven’t got what it takes’. In 2017, after playing a character in an unflattering fat suit opposite Chris Hemsworth in Universal Pictures’ The Huntsman: Winter’s War and shooting a special episode of the cult BBC hit Inside No 9, work dried up. ‘I think I was feeling a bit lost. I remember going to countless auditions and not being… I don’t know, just not confident and not making bold choices,’ she says. ‘I find it hard to find my voice or to speak up in spaces that are dominated by people who had a better education than me.’

On her forearm Roach has a tattoo of a kite with the inscription ‘let go’ in the loop of its string. And that is what she did. She and her partner Jack, an events promoter, bought a house in Bristol, and she took a six-week course in DJ-ing as part of an initiative to get more women into the music industry. Her DJ name is Dave, she says. ‘I felt that if I was a guy DJ, I’d get booked more.’ Just as she was starting to worry that the ‘rainy day’ money she’d banked from Universal was running out, the BBC came knocking with a part in Killing Eve.

She and Jack got married in Brecon in 2018 in a marquee in a field with a male-voice choir, the sun setting behind Pen y Fan, with dancing into the night. Their daughter, three, has given them ‘everything’ (including, right now, a head cold). ‘She loves dance,’ says Roach. ‘We have dance parties in the kitchen. She’s discovered how to use Alexa, which feels dangerous. But right now, we’re listening to a lot of Chappell Roan and Sugababes.’

And the work? She’s been filming Amazon Prime’s new Harlan Coben drama Lazarus in Manchester with Sam Claflin and Bill Nighy (‘I could listen to his stories all day’). And she is proud of Nightsleeper. ‘There have been years where I haven’t loved this career,’ she says. ‘So to love it again now feels wonderful. To be in this position leading a BBC show is not lost on me.’

I move to leave and check the route on my app. Honest to god, it reads, ‘Transport for London cyber incident: live tube times currently unavailable’. Spooky timing, I say to Roach. ‘I wonder how many people will buy a bike after watching the show,’ she replies.

Idea for season two: the hackers get hold of an e-bike.

Nightsleeper is on BBC One tonight and concludes tomorrow at 9pm; all episodes are available to stream on iPlayer

Stylist: Cassie Walker Graham. 

Hair: Chad Maxwell. 

Make-up: Min Sandhu.