It was the scale of the thing that most surprised Ross Anderson.

The Paisley-born actor arrived on the set of Angelina Jolie's new wartime film Unbroken to find a life-sized replica of a Japanese prisoner of war camp had been built in Australia. And as well as the huge cast and crew hundreds of extras were milling about waiting to be filmed.

"We had 300 extras working with us every day," Anderson remembers as we sit in a five-star hotel in London, "and they had an amazing military instructor. He trained these guys to work as a unit for filming purposes, because, as you can imagine, working on that scale with that many people has the potential to be quite hectic."

And yet, Anderson says, Jolie was on top of everything. The Hollywood star, who has recently announced her retirement from acting, proved the perfect director. "She was amazing. She had huge set pieces and a crew to orchestrate, which she did, and then she'd come to us for the much more intimate scenes and gave the time to concentrate on the detail and the human aspects which, at the end of the day, it's about. She made a real effort to give that focus and to allow us to play, even sometimes improvise. It was great to have that kind of trust, not someone coming in and saying do it that way."

Unbroken is the story of 1930s Olympic athlete and US air force captain Louis Zamperini who survived the crash of his plane in the ocean south of Hawaii in May 1943 and 47 days adrift in a dinghy only to be captured by the Japanese navy and sent to a POW camp where he was mistreated abominably by his captors.

Anderson plays a Scottish POW called Blackie in the film, one of the many who populate this huge, old-fashioned Hollywood movie. "Angelina always made it clear the importance she felt it was an ensemble piece," he says. That said, it's a breakout role for the Scottish actor.

Anderson, 27, has now made three films in quick succession. Unbroken will be the first to appear in cinemas but he has also completed The Silent Storm, a drama set on the Isle of Mull in which he appears alongside Damian Lewis and Andrea Riseborough and a new, dark and gritty version of Macbeth which stars Michael Fassbender and Marion Cotillard. "I love working and working hard," he admits.

It's the way he was brought up. Anderson's family moved to Bo'ness in West Lothian when he was five and over the years he always helped out in his father's businesses - which include a funeral business and the Bo'ness Motor Museum. Anderson even had a spell as a lifeguard at the local pool when he was a student.

But acting was the only career he ever really wanted to pursue. "I'd picture myself doing something else and go 'no'. 'Can I picture myself as a doctor? Well purely from a grades question that would never work'." So instead he studied at Telford College in Edinburgh and then the Drama Centre London before winning a role in the National Theatre of Scotland's play Black Watch on a world tour.

Other theatre parts followed and then a part in the BBC drama series Privates about National Service last year. There do seem to be a lot of military roles on his CV already but in The Silent Storm he does get to dance around with Riseborough and get beaten up by Lewis.

Anderson has old-school movie star looks though he says he was a late starter when it comes to girls. His first kiss must have been "at some disco at high school. I'm sure I was awful. But you'd have to ask my girlfriend how I am now." The scene with Lewis apart what about his last fight? "There's been a few throughout the years. I had a few in school. I started off at the lower end of the scale of popularity. I received a few kickings and then my parents were 'right, sort yourself out.' I got a set of weights for my 13th birthday and, yeah, I started to stick up for myself after that. But I'd rather take you for a drink than fight about anything."

Unbroken opens in cinemas on Boxing Day.