Fionn Whitehead: "Dunkirk set the mood for the rest of the war"

The Big Issue: This is your first major role and it is a very major movie. Was it a bit of a baptism by fire?

Fionn Whitehead: Yeah I guess so but a blessing and a curse. Never knowing anything different, it was take it as it comes. You acclimatise quickly. First day on set walking around seeing these huge constructions, real Spitfires and thousands of extras is jaw dropping but after a while you get used to it and it was only looking back recently that I was realising how crazy it was.

This story isn’t an all-guns-blazing victorious march ahead, it’s about people running for their lives

What does Dunkirk mean to your generation?

I did learn a bit about Dunkirk when I was at school, but it’s not touched upon as heavily as other events in the war, probably because it is seen as a defeat in a lot of ways, although it was turned into a celebration. I think also the spirit of Dunkirk set the mood for the rest of the war in Britain – this real clubbing together, all in it together – it was really the turning point when everyone realised they had to get together and work as a team. That is one of the most interesting things about this story, it isn’t an all-guns-blazing victorious march ahead, it’s about people running for their lives.

Did making the film change your perception of the war?

One of the craziest things was how open all the soldiers were – they were on this beach, and it is just huge stretches of beach with nothing to cover you. They were having to sleep on the sand and in the dunes, places with really scarce cover and just getting the hell bombed out of them. This real survival instinct kicks in.

What preparation did you do for the role?

I went out to location two weeks early and trained with the stunt team, doing some circuit training and swimming in the Channel in battle gear and a wool trench coat. Once I remember, not only did it get completely waterlogged and weigh me down, it also acted as a sail against the current.

How are you enjoying your last few weeks of being an unknown?

Maybe I’m a bit naïve, but I have never had my focus on that at all. Living in London really helps, it is such a busy place, everyone has their own things, their own lives going on. So it is easier to get around and live your life. I lead a pretty normal life – I get trains everywhere, cycle around, eat food in normal people. I hope it won’t change.

• Read more about the Dunkirk evacuations and the new film in this week’s Big Issue – featuring a trip back to the beaches with the film’s producer Emma Thomas and historian Joshua Levine, plus interviews with Harry Styles, Kenneth Branagh and Cillian Murphy