Paul Darrow, who played Kerr Avon in BBC sci-fi series Blake’s 7, has died aged 78 following a short illness, a spokesperson for the actor has confirmed.

Darrow achieved cult status with his performance as the morally ambiguous computer expert Avon, who fought alongside outlaw Blake (Gareth Thomas) against the totalitarian Federation, not because Avon felt it was right, but because he believed it was the best way to stay alive and get rich enough to retire in exile.

The popular BBC One series, which ran from 1978 to 1981, was created by Terry Nation. Darrow took over as lead character for the final two series of the show after Thomas departed, and the character’s sardonic wit and Darrow’s deadpan delivery made him a favourite among fans.

As well as Blake’s 7, Darrow had a scene-stealing guest role in 1985 Doctor Who story Timelash, and between 2009 and 2014 had a recurring role in Law & Order: UK as first Judge, then later Justice Prentice. He had also featured in long-running British soaps Emmerdale and Coronation Street, and played the role of the Sheriff of Nottingham in the 1975 BBC series The Legend of Robin Hood.

Darrow, centre, with the cast of Blake’s 7 in its final two series. Photograph: BBC

Born in 1941 in Surrey, Darrow studied at RADA and while there shared a flat with John Hurt and Ian McShane. He married Janet Lees-Price in the 1960s after meeting her on the set of ITV’s medical soap opera Emergency – Ward 10, which they had both featured in. Lees-Price died in 2012.

Darrow had suffered health issues in recent years that led to the amputation of one leg and the partial amputation of another. In 2018 he appeared on an edition of Pointless Celebrities in a wheelchair alongside fellow Blake’s 7 cast member Michael Keating.

He had enjoyed a long career in theatre, including playing Samuel Vimes in a touring production based on Terry Pratchett’s Discworld novels, but he will remain best known for Blake’s 7. His name had often been connected with attempts to reboot the show for television, and he had reprised the role of Avon multiple times in audio plays.

Speaking to the BBC, Darrow’s friend and PA Maureen Marrs, said: “Over three decades I have been Paul’s confidante and have had the immense privilege of being part of his life. A star has gone out today; the world will be a darker place without him.”