SCOTTISH screen star Kelly Macdonald has joined the cast of hit BBC crime drama Line of Duty.

The Glasgow-born actress will play Detective Chief Inspector Joanne Davidson in the sixth season of the show, which also stars fellow Scot Martin Compston, who portrays Detective Sergeant Steve Arnott.

Kelly, 43, is best known for her roles as Diane Coulston in Trainspotting and Margaret Thompson in Boardwalk Empire.

Her character in Line of Duty is the senior investigating officer of an unsolved murder, whose unconventional conduct raises suspicions at the anti-corruption unit.

Filming of the new series is due to start next year with stars Vicky McClure, who plays Detective Inspector Kate Fleming and Adrian Dunbar, who portrays Superintendent Ted Hastings, also set to make a return.

Line Of Duty writer and showrunner Jed Mercurio said: “We’re honoured that Kelly Macdonald will join Martin, Vicky, and Adrian in series six of Line Of Duty.

“DCI Joanne Davidson will prove the most enigmatic adversary AC-12 have ever faced.”

Simon Heath, chief executive and creative director of Line Of Duty’s production company World Productions, added: “The Line Of Duty team have always been huge fans of her work, so we’re thrilled Kelly has agreed to join us this series to pit her wits against AC-12.”

Macdonald was described as “one of the UK’s most versatile actors” by the controller of BBC drama Piers Wenger.

The fifth series of the popular police procedural show aired earlier this year, with Stephen Graham in the guest lead as Detective Sergeant John Corbett.

Its final episode drew more than nine million viewers when it aired in May, making it the most-watched drama since Mercurio’s Bodyguard, which aired in 2018.

Last week, we reported that Greenock-born Martin Compston, 35, delighted fans by sharing details of his catch-up with co-stars Vicky McClure and Adrian Dunbar on Instagram.