Martin Compston describes Line of Duty series five in just one word

Speaking to RadioTimes.com, the actor who plays DS Arnott in the show and stars in new film Mary Queen of Scots – sums up the new Line of Duty in just one word: “Unpredictable.”

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“It’s been a cracking year and we have great guest stars and the scripts are phenomenal,” he elaborated. Stephen Graham has joined the hit crime drama in a mystery role.

“It has the potential to be the best ever with the cast and the actors we have, but you never know," he said. "I’m really excited, I really am."

While fans wait for the return of Line of Duty, Compston appears in Mary Queen of Scots starring Saiorse Ronan as Mary, with Margot Robbie playing her nemesis Elizabeth I.

The actor told RadioTimes.com that as a proud Scot he liked appearing in a film which told such an important chapter of Scottish history, describing the movie as “the ultimate political drama”.

Compston plays Earl Bothwell, Mary’s second husband, who was instrumental in killing her first, Lord Darnley. He was also powerless to stop Mary’s eventual imprisonment in England and ultimate death, but the actor insisted that he has portrayed his character in a more positive light than he is usually depicted.

“The way I see it he keeps his cards close to his chest and he think he saw himself as her protector,” said Compston. "He always tries to act as her protector, but in the end he can’t be that.

“In our version Mary’s the hero and she wins in the end because [her son] James is crowned [King of England and Scotland].”