Harry Styles cried when he first watched 'Dunkirk'.

The 23-year-old singer and actor makes his movie debut in the upcoming drama, which sees him play the role of soldier Alex in the World War II drama about the famous Dunkirk Evacuation, and the star has admitted he was overcome with emotion when he observed himself in action at the film's premiere in London's Leicester Square last week.

Speaking about his reaction to his pal Nick Grimshaw on his BBC Radio One Breakfast Show on Monday (17.07.17), the One Direction heartthrob said: ''The first time I watched it, because I hadn't seen anything and how he'd put the story together, I was more watching to see how the story was, and when I watched it at the premiere in London it got me a couple of times. There were a couple of emotional bits but I didn't know if I was allowed to cry at a film I'm in, but yeah it was really emotional. It's a very personal experience, even if you're watching it in a cinema full of people you feel like you're watching it on your own.''

The 'Sign of the Times' hitmaker, who appears in the film alongside Tom Hardy, Cillian Murphy and Mark Rylance among others, has admitted he felt overwhelmed on the first day of filming because he was ''scared'' of the film's director Christopher Nolan.

The dark-haired hunk said: ''I think walking onto the set was so overwhelming. Trying to imagine something of that size and when you actually see it, it's insane. And I was pretty in awe of him [Christopher Nolan] the whole time I was filming. I was a bit scared of him.''

And Harry has admitted he was congratulated by his fellow 1D bandmates, Niall Horan, Louis Tomlinson and Liam Payne, for his performance in the film.

When asked if he had been contacted by his the group, he simply said: ''Yes''.