One of the veteran cops in hit drama New Tricks, Alun's been a familiar face on screen since the 1970s.
Alun stars in New Tricks, the drama about cops coming out of retirement to aid modern day investigations. His co-stars are Amanda Redman, James Bolam and Dennis Waterman.
He played Inspector Bucket in the BBC's 2005 adaptation of Charles Dickens' Bleak House. The suspenseful tale about the injustices of the 19th-century English legal system was a ratings success, and won a BAFTA for Best Drama Serial.
He played Mr Fang in another Dickens adaptation, Roman Polanski's 2005 film Oliver Twist. He's such a Dickens fan that in 1999 he turned down a role in a Clint Eastwood film to take on the role of Daniel Peggoty in David Copperfield. Other Dickens' TV adaptations he's appeared in include Oliver Twist and Nicholas Nickelby.
Alun's screen debut came in the classic Michael Caine gangster movie Get Carter. Other early roles included parts in Whatever Happened to the Likely Lads?, The Likely Lads film, Softly, Softly and The Sweeney.
His many other TV roles include Austin Donaghue in Our Friends In the North, with Christopher Eccleston and Daniel Craig; Detective Chief Inspector Frank Jefferson in In the Red with Warren Clarke, Stephen Fry, and Richard Griffiths; and George Mole in Adrian Mole: The Cappucino Years, alongside Alison Steadman.
Film credits include The French Lieutenant's Woman, Krull, American Friends, Patriot Games and Braveheart.
He played the High Constable in Sleepy Hollow, alongside Johnny Depp, museum curator Baltus Hafez in The Mummy Returns and appeared with Hugh Jackman and Kate Beckinsale as Cardinal Jinette in Van Helsing.
In the 2000s, TV parts have included the role of retired latin teacher Jim in When I'm 64, Samuel Evans in Carrie's War and Neil Henshaw in Andy Hamilton's Bedtime.
He was Academy Award nominated for his performance in The Childeater, a short film by Jonathan Tammuz, and nominated for the Best Actor Award by the Royal Television Society for his performance in This Is Personal: The Hunt for the Yorkshire Ripper in 2000.
He won a Laurence Olivier Theatre Award for his 1993 Royal National Theatre performance as Sweeney Todd.
His son, Joe Armstrong, is also an actor, best known for his role in Robin Hood.
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