Dominic Cooper: 'My problem was having compassion for a monster'

On paper, the decision to cast Dominic Cooper as Uday Hussein and his body double, Latif Yahia, in The Devil's Double is as surprising as Peter Sellers turning up as an Indian in The Party. Thankfully, advances in make up and Cooper's naturally swarthy looks meant that he did not have to get out the boot polish in order to play an Iraqi.

Directed by the director of the Bond film Die Another Day, Lee Tamahori, The Devil's Double is set around the Iraqi invasion of Kuwait and the subsequent Operation Desert Storm. Stock footage of George Bush and American troops in action is juxtaposed with Cooper's dual performance. In a traditional battle between good and evil, Uday rapes, curses and murders his way through the picture, much to the disbelief of his double. It is an extreme and liberal rendition of "the truth", in which a thriller plot and exaggerated caricatures take priority over realism and social accuracy.

Cooper, who was born in London, is noted for playing white middle-class characters, whether preparing for Oxbridge exams (The History Boys); frolicking in a Greek island paradise (Mamma Mia); or, as a rebellious rock star, frolicking with Independent journalists (Tamara Drewe). None of these roles suggests a suitability for the role of a wild, unhinged son of a despotic Iraqi leader, although that mix of silver-spooned, holiday-loving figures with delusions of grandeur and a penchant for ladies – and the occasional man – is perhaps not so far off Cooper's portrayal of the crazed Uday Hussein.

The enthusiasm with which the 33-year-old Briton chased the role is indicative of his desire to play parts that lie outside his comfort zone. Cooper admits: "When I first read [The Devil's Double], there were lots of people attached to it, directors and actors, so it always seemed like a really far-off prospect, but I very much pursued it and kept asking about it. It's the one script that I actually remember pursuing constantly."

His perseverance paid off, yet once he had landed the part the actor knew that he would have to approach it in a way that challenged his acting instincts. "My biggest problem when I started talking to Lee about it was having minimal compassion for a man who was ultimately a monster, a man who had no restrictions and control and did things for reasons I couldn't fathom at all. I have always worked from that place, that if you are going to inhabit someone and get under their eyes, you need to have empathy."

Unable to relate to Uday at all, the star had to go back to the drawing board. "I went back and thought, 'OK, lets think why this person is messed up.' What intrigued both myself and Lee was the notion of dictators' sons who are more often than not uncontrolled and they have a wealth of riches and whatever they need. When I thought about what he must have been subjected to at an early age, then I could start to kind of build upon, or excuse – no, 'excuse' is wrong, because there is no excuse – but at least understand the complexities of why a human being can behave in this way."

Cooper considered the feelings that he had experienced when he began to sample the high life and the perks on offer to a successful, good-looking young actor on the international stage.

"In whatever work environment, whether we admit it or not, there is always a little part of us that has been or will be tempted by a lifestyle for the wrong reasons," he says. "I noticed it with the first studio film I did. [Mamma Mia!] You suddenly get treated like an absolute king. You're flown around the world, staying in beautiful places, in places I wouldn't in my wildest dreams stay in, or never be able to afford to stay in, and you finish that particular job and you realise, 'Oh, that's not my actual life,' and you're back in Deptford, down your local, and you realise that you've been a little bit skewered by what you have been through and seen.

"It's very bad. But it's a good lesson, I think, if you can get a taste of it and experience it and then not get tempted by things for the wrong reasons you can relate to it."

Another tool available to the actor was Uday's actual body double, Latif Yahia, who wrote the book on which the film is based.

I had Latif to chat to, which I did for a few hours when I first got the role," Cooper says. "It was great to know that he was there if needed, but we didn't want to make this into a biopic. There are certainly sensitive issues and what we were doing was taking what is essentially an incredible story, about a person [who] ultimately had to be someone that they are not. The whole film is someone pretending to be someone that they are not. And then what was important was that we built upon these characters and created much more, verging on the cartoonish."

Yahia is an intriguing character. At the end of the film, it is written that he is a hard man to find, living in Ireland with his wife and two kids. Not too hard, it turns out – on the day that I interviewed Cooper, he was around. When I asked him how he felt about the movie, he said: "It was very well done, close to the truth, a very high percentage."

The film's story is that Yahia was, by and large, a reluctant player in the madness of Uday Hussein, a player who tried his utmost not to partake in rape, torture and murder and who was one of the few people willing to stand up to the criminal. It is a heroic tale, and it is not remotely believable. Cooper has his own queries about the implications of Yahia's work as a body double.

"There is always the question of whether he was implicit, did he get involved," the actor says. "Surely it was a matter of saving his own life. I think he perhaps got seduced by a world of riches. Who knows? He is a wounded man and even if he went through a fraction of one of the things this person went through on-screen, it's truly traumatic and you just don't know. It's his story and what you believe of it is up to us."

It is hard to tell what this grandstanding, leading-man performance will do for Cooper's career. His trajectory has been skywards since he started with small parts on TV shows and moved on to the success of The History Boys, on stage and then on the screen. His cinema roles have included hits like Mamma Mia! and An Education and The Devil's Double arrives as the superhero blockbuster Captain America: The First Avenger hits our screens.

Playing the inventor Howard Stark in a big budget comic-book adaptation was the fulfilment of an ambition.

"It was one of those childhood dreams," Cooper says, "of desperately wanting to say 'the flux capacitor'. I create this quite interesting futuristic automobile in Captain America and while doing the scene I thought, 'I'm actually in Back to the Future.' I actually did exactly what I dreamed of when I was a small child in the cinema and said, 'One day I would love to be that person in that film.' Making Captain America felt pretty cool."

Childhood ambitions fulfilled, Cooper's next role is a much more weighty affair. He plays the photographer Milton Greene in My Week With Marilyn, Simon Curtis's film about on-set shenanigans between Marilyn Monroe and Laurence Olivier during the making of The Prince and the Showgirl, in 1957. Michelle Williams plays Monroe; Kenneth Branagh is Olivier.

Cooper says: "It's an amazing period of time, featuring a kind of intriguing collaboration of two worlds ultimately colliding. The flash American studio iconic figure and forward-thinking people whisked in to do this big film they were excited about, who were then met with extraordinary sterile opposition in the form of Olivier, who was directing this movie."

He describes the movie as "a sweet story". "I say sweet," he adds, "but on the one hand it's sweet and [there is] the romantic side of it and [on] the other side it's terribly devastating, actually. She [Monroe] was ill with something people at the time did not know much about – she had a womb infection, which meant she was in an extraordinary amount of pain most of the time. And then the drug dosage was completely different in the UK than it was in America, so when Milton was getting drugs from English doctors it was the wrong dosage. She was spiralling out of control."

'The Devil's Double' is out on Wednesday. 'My Week With Marilyn' is released later this year