Martin Compston listens to himself speaking to perfect his 'Line Of Duty' accent.

Martin Compston as DI Steve Arnott

Martin Compston as DI Steve Arnott

The 36-year-old actor - who plays DI Steve Arnott in the BBC One drama - originally hails from Scotland and he admits it can be difficult to get the accent spot on, especially in the long scenes.

He said: "It can be hard, that dialogue on its own would be hard anyway, throw the accent in there ... The scene we did the other night, 30-pager, trying to juggle the accent at the same time. When we're away from it for a long time, when I do that voice I can hear him, it's like a costume.

"I walk about all day with him in my ears. It's just graft. I'm not naturally good at accents. I need to work harder, which then makes me better because I'm not complacent with it.' If you're in these scenes with these amazing actors, amazing guest stars, it's intimidating enough without worrying about the accent. Speaking to the wife and stuff I'll drop it, I very much stay in it on set."

Martin turned to "soup and water" to get rid of his lockdown weight gain and fit back into Steve's suits.

Speaking about his lockdown weight gain, he added: "I'd just finished filming 'The Nest', had my top off a fair bit in that ... I'm usually a 32, got down to 30, now I've got these tailored suits for Line of Duty. We start filming, lockdown happens, up to about a 34… I couldn't get them on. I couldn't even get the shirts buttoned. Two weeks of hours on an exercise bike, eating soup, water … miserable."

Meanwhile, Vicky McClure - who plays DI Kate Fleming - recalled how she once flew on Madonna's private jet in her early career, before heading straight back to her office job the next morning.

Speaking on The Jonathan Ross Show, she said: "I didn't leave my office job until I did This is England ‘86. I didn’t have a steady career, I had bills to pay ... They were really good to me, making sure I had time off. I’d done this film with Madonna, gone to Berlin on her private jet. Got back that night, I remember the next day, I was in the office as fire warden, HR, vending machines and someone came up to me and they said, 'I just ordered a mocha and I got a latte…' I was like, 'I’ll go sort that in sec.'"