Line of Duty's Martin Compston: 'I haven't played a nice guy in a while'

Plucked from obscurity by Ken Loach, the Scottish actor has gone from working-class kid to star of the UK’s favourite drama. Now, he’s in a new thriller – and, for once, without an English accent

Every actor has a war story about a disastrous audition, but Martin Compston’s is particularly chaotic. In 2002, the Scottish actor – then in his late teens – flew down to London to audition for a guest role in an ITV period drama. Just one problem: he had been sent the wrong lines. “So they gave me what I was supposed to do and asked me to come back in 15 minutes,” he says. “It was a three-page monologue from a suicidal kid telling a doctor why he wanted to take his own life. I was so angry, it was all a blur.”

The experience was enough to make Compston consider chucking in his fledgling acting career. “My agent at the time called and I told him: ‘I don’t think this is for me.’ And then he said, ‘you got the part.’ I felt like maybe I can do this, maybe there’s something there.”

It was a turning point for Compston, who had not long been plucked from obscurity to play the lead in Ken Loach’s hardscrabble drug drama Sweet Sixteen. Well, sort of obscurity: the Celtic-obsessed teenager had captained Aberdeen’s youth side and was offered a contract with his local football team, Greenock Morton, before his career change.

After Sweet Sixteen, he did more TV, starred in acclaimed films such as Andrea Arnold’s Red Road, and eventually ended up landing his most well-known role to date in Line of Duty, playing corruption bloodhound and baby-faced lothario DS Steve Arnott (“he’s that overdressed wanker at work who is having all the office affairs”, he says, lovingly). He recalls the challenge of convincing industry types that he could play more than just a wiry Greenock delinquent.

“People assumed I was just my character from Sweet Sixteen,” he says. “I come from a working-class family but me and my brother were well looked after, we had everything we needed, we had a good education. So it was important to get in rooms with people to show them I was different from that kid.”

Line of Duty has been a gripping British drama staple since it debuted in 2012, but the show’s fifth series elevated it from ratings hit to genuine phenomenon, with Stephen Graham following in the footsteps of Thandie Newton and Keeley Hawes with an explosive guest appearance. “It just took it to a whole other level,” says Compston, recalling a day when he was essentially kettled in a train station by fans desperate to learn the identity of mystery bent copper H. After affecting a South London twang as the workaholic detective, Compston is now back to a Scottish accent – albeit a Dundee one – for Traces, the first original drama from the UKTV channel Alibi.

The series centres around Emma (Bafta winner Molly Windsor), a young forensic lab assistant whose return to Dundee makes a local cold case unexpectedly hot again. You might expect Compston to be playing the cop who swoops in to lead the investigation, but this is a lanyard-free role: his character, building contractor Daniel, is Emma’s love interest.

Both characters are wrestling with family trauma and troubling secrets – through his work, Daniel is implicated in a lethal nightclub fire – but for a drama about coldly analysing forensic evidence, Windsor and Compston bring an appealing charge of blood-and-guts passion. “It was the sort of part I hadn’t played for a while,” says Compston. “Daniel’s a nice guy trying to do the right thing and then he’s got this wee firecracker in his life, they sort of consume each other. His head is a bit of a mess when we meet him and things just get more wild.”

Compared to prickly Arnott, it is a surprisingly tender, troubled portrayal. Compston previously shared a flat with Kyle Falconer of Dundee rockers The View and drew on that experience while approaching both his character and the local accent. “I’ve had a unique insight into the mental workings of Dundonians,” he says drily.

The days of flatsharing are now well behind him. In 2016, Compston married his American girlfriend, Tianna Flynn, in Greenock but home is now Las Vegas, complete with pool and – as he proudly revealed on Instagram – a customised Tennent’s lager tap. Not that he’s had much chance to use it, with work keeping him on the road. “I haven’t been in Vegas since April and I won’t get back there until Christmas and then I’ll be leaving again for four months,” he says, recounting a hectic schedule that includes shooting the sixth series of Line of Duty in Belfast early next year.

He is also currently finishing filming BBC One thriller The Nest, in which he and Peaky Blinders’s Sophie Rundle star as a childless couple who recruit a mysterious surrogate. The show is set in Glasgow, which also means he can use his own accent at long last. “The script feels naturally how I would speak, and I haven’t felt that for a long, long time”.

Getting to play Scottish in both Traces and The Nest has been a treat; “I’m always chuffed to bits to get anything on screen that showcases part of Scotland”, he says. But, ultimately, AC-12 is never far from his mind. “I’m looking forward to getting back, putting the waistcoat on”, he laughs.

• Traces begins tonight on Alibi at 9pm