Disney princesses, corrupt coppers... it’s all in the Line of Duty for Kelly Macdonald

Kelly Macdonald says her upcoming role in Line of Duty felt as iconic as playing a Disney princess.

The actress, 45, one of Scotland’s most successful screen stars, is following Keeley Hawes and Thandie Newton as a guest star in the top-rated crime series. The role is traditionally pivotal as viewers are wrong-footed by twists and turns in the police procedural thriller set in AC-12, an iconic anti-corruption unit.

In the off-season between series of US hit Boardwalk Empire, Macdonald won a coveted role to voice the lead in the Disney animated movie Brave, in which she played Merida.

And yesterday she said being cast in Line Of Duty felt similar to the Disney role, adding: “It’s the guest lead thing. When I was doing press for Brave, I was like, ‘I’m a Disney princess – whoa, what?’ Being a guest lead in Line Of Duty is like that.”

Macdonald added she had no idea as she filmed each tough-going Line of Duty scene just how good or bad the officer she was playing might be, as writer Jed Mercurio’s scripts were only released to the actors a few episodes ahead of filming. She said: “Jed had called my character enigmatic, so I clung on to that. We did a read-through and it was pretty hard going. I think we read three episodes, and I was just a shell of a woman by the end.”

Fellow Scot Martin Compston is back with co-stars Adrian Dunbar and Vicky McClure in the new series, which begins on BBC1 on March 21. He plays Steve Arnott and maintains his English accent off-set.

Compston said: “I’ve got two very understanding co-stars who put up with Dick Van Dyke impression for the first week or two.”