Tributes have been paid to "gladiatorial" Game of Thrones and Porridge actor Peter Vaughan following his death at the age of 93.
Christopher Eccleston, who played Vaughan's son in Our Friends in the North, said he had learned more from Vaughan than anyone else in his career.
He told BBC Radio 4's Front Row the actor was "wonderful to work with".
Porridge writer Dick Clement told the programme Vaughan made the character of Grouty "his own" in the sitcom.
'Celebrate fantastic life'
Clement said: "He had a wonderful quality of being menacing at the same time funny, not an easy thing to pull off.
"He was a real adversary for [Ronnie Barker's character] Fletcher, someone you knew you wouldn't mess around with."
Clement highlighted the "brilliant films" in which Vaughan also appeared, including The Remains of the Day, Brazil and Straw Dogs.
"If you are still working in your 90s, which he was, you can only celebrate what was a fantastic life and be glad of it," he added. "I think he was a consummate actor and I feel very privileged to have worked with him."
Speaking about Our Friends in the North, Eccleston recalled: "When he was first introduced to me, the first thing he said to me was, 'Hmm, I don't like the look of you.'
"And I said, 'No, I don't like the look of you.' And me and Peter were off from then.
"Peter was gladiatorial as an actor.
"You've got to remember that you had Daniel Craig, Gina McKee, Mark Strong and myself all at the beginning of our careers, all very opinionated, all very energised, but there was no more intense actor on that set than Peter Vaughan."
Vaughan played Felix Hutchinson in the 1990s drama, a character at odds with the younger generation and who developed dementia.
Eccleston said the actor's "subtlety" made him stand out: "Little things, like obsessive gestures like rubbing the table."
Vaughan also played Maester Aemon in four series of HBO's Game of Thrones, his character being a blind, scholarly mentor and guide to Samwell Tarly, played by John Bradley, and Jon Snow, played by Kit Harington.
Bradley said of his co-star: "His enthusiasm, passion and kindness were matched only by the power and precision of his performances.
"He could terrify and enchant in equal measure. He taught me so much but only ever by example and it was an honour to be his colleague."
Owen Teale, who plays Ser Alliser Thorne in the series, told ITV News: "Peter was a very inspiring character to me, I think to anybody.
"He was a gentle giant, he really was. And as I speak about him I miss him very much. And the memories I have I cherish."
Vaughan's many other roles included parts in TV shows Citizen Smith, Bleak House and Chancer.