Michael Caine has been a firm fixture in six of Christopher Nolan's films, so it was only right that he made a cameo in the director's latest big-screen offering. But unlike his prominent role in 2005's Batman Begins, his appearance in the war epic Dunkirk was a blink-and-you'll-miss-it moment.

Nolan has confirmed that while Caine doesn't get any screen time, the 84-year-old star is the officer that talks to Tom Hardy's RAF pilot over his radio in the film.

"It's shocking to me that a lot of people haven't [noticed him], when he has really one of the most distinctive voices in cinema," Nolan told online publicationNJ.com.

"I wanted very much to squeeze him in here. It's a bit of a nod to his character in Battle of Britain. And also, it's Michael. He has to be in all my films, after all."

As well as playing Bruce Wayne's butler Alfred in the Dark Knight trilogy, Caine starred in 2004 thriller The Prestige and sci-fi blockbusters Inception (2010) and Interstellar(2014).

A minor role in WWII drama Dunkirk meant that Caine didn't have to endure the gruelling hours on set or risk the same type of injuries his co-star Harry Styles suffered.

The Sign Of The Times singer recently revealed he felt "numb" once production had finished. "There was a couple of little [injuries], I was a little numb by the end of it. I did something to my wrist that I don't even know, it keeps going," he told Capital FM's Roman Kemp. "Stuff would fall on my head and things would rip off the wall, it was amazing. The stunt guys really went through it and it made me feel like a wuss."