Harry Styles wowed by Christopher Nolan's work ethic

Hollywood newcomer Harry Styles was impressed by Christopher Nolan's work ethic on the set of Dunkirk.

Triple Oscar nominee Christopher is back behind the camera with the new war drama, which tells the story of the evacuation of Allied soldiers during World War II.

Dunkirk marks One Direction star Harry's first movie, and being on set was an eye-opening experience for the 23-year-old and his young co-stars.

"He leads by example, so much. He's the first one there and the last one to leave," Harry said of the filmmaker in an interview for Warner Bros.

"I was always told if you were ever to do a film, you'd hear the director shouting the directions from three miles away in a tent," added British actor Tom Glynn-Carney. "But Chris is there the whole time. You see the camera there and Chris there (next to it)."

Christopher was just as complimentary about the young stars he cast in the movie, many of whom are new to the big screen. Actors such as Harry, Tom and Fionn Whitehead star alongside the likes of Kenneth Branagh, Tom Hardy and Mark Rylance.

"The traditional thing in Hollywood movies is to cast 28-, 29-year-olds, 30-year-olds, and pretend they're younger," Christopher said. "We wanted to cast people of the right age, we wanted kids who would experience these events, in the way people would have at the time. It was very important for us to find interesting, fresh faces to do that."

Dunkirk hits cinemas from 19 July (17).