When director Christopher Nolan was casting for his Second World War film Dunkirk, he didn’t see One Direction star Harry Styles and think, “There’s a movie star.”

Styles, 23, who gained fame with the British pop band and has recently embarked on a solo career, plays a British soldier in Nolan’s suspense-thriller about the evacuation of Allied soldiers from Dunkirk, France, in May and June of 1940.

“You can’t worry too much about previous roles or Harry’s celebrity,” Nolan says. In separate interviews, the filmmaker has bluntly stated that he wasn’t aware how famous the pop star was.

“My job as a director is to see the potential in the people we are casting whether you’re talking about someone who has never done a film before or Harry or someone who is more experienced like Mark Rylance or Ken Branagh,” he tells reporters at the Barker Hangar in Santa Monica. “You have to see the potential for them to do something they’ve never done before. That’s really the idea. If you don’t pick the right person who’s up for the challenge, they won’t get anything out of the experience.”

Dunkirk also features Cillian Murphy and Tom Hardy, and stars newcomer Fionn Whitehead.

“I think the audience, when they come to a film, if we all do our job right, they become invested in the world we’ve created and they take that on its own terms.”

Styles, who hits the road later this year for a worldwide solo tour, says working with Nolan was a dream come true.

“I just felt very lucky to be on the set,” Styles says. “I’m personally a fan of his work and I got to be with a group of actors that I’m a fan of as well. I was just grateful to be involved.”

MDaniell@postmedia.com

