Kiefer Sutherland grew up unaware of dad Donald's success

"So I'm 17 years old, I've moved to Los Angeles and a friend had this incredible collection of all of my father's films on VHS [Video Home System]," Kiefer says.

Over two or three days, the teenager binge-watched his father's work.

"When I see his work, it's just astounding," Kiefer says.

He told his father: "I didn't realise how special and great you are as an actor."

"And he was so sweet - he kind of almost cried and said, 'Well, how could you? You were just a boy.'

"And that was a really special moment for both of us and our relationship kind of took a turn at that point."

When the pair later worked together, on 2016 western Forsaken, "It was a great time to spend together," Kiefer says.

Set in 1872, Forsaken, focuses on embittered gunslinger John Henry Clayton's return to his hometown and his attempts to build bridges with his estranged father.

Their on-screen characters are in fierce conflict - but the off-screen relationship between the two actors was harmonious.

"I just loved watching him do his thing," Kiefer says.

Known for an array of major parts, including in The Dirty Dozen, M*A*S*H, Don't Look Now, Klute and Six Degrees of Separation, Donald Sutherland was not always destined for an acting career.

From a small fishing village in eastern Canada, he was part way through an engineering degree at the University of Toronto when he quit and went to England to follow his dream of becoming an actor.

"The courage to do that is extraordinary," Kiefer says.

An early appearance on British television came in a 1960s production of Hamlet, with a young Michael Caine.

But his big break was in The Dirty Dozen, in which, at first, he had a non-speaking part but was picked for something far bigger, apparently at random, by director Bob Aldrich.

"He didn't even know my name," Sutherland said.

"We'd all had our hair shaved off. He looked around the table and he said, 'You with the big ears, you do it.'"

Kiefer describes this as "a real breakout moment for my father".

But the fact he then "managed to be in films that were incredibly important each decade, is a testament to his capabilities as an actor - and I'm incredibly proud of him for it", he says.