“It was actually incredibly exhilarating to be in the middle of it. We’d all be sitting there in the rain and mud chatting to each other before a take and then we’d get up and dash through explosions, which were going off on all sides of us. There were markers dotted across this battlefield where the explosions were and then we’d start filming and they’d take them away and start the rain machines, so our vision would be reduced by about 70%. Also, the rain does something to performance. Bryan Kirk, the director, says that when it’s raining that heavily there’s a level of intensity that almost can’t be gained any other way. When you have to compete with the rain and still be able to communicate with each other, the level of intensity in your performance soars. And the water in those rain machines seems a lot colder and a lot harder than the rain you get from normal clouds.

“It wasn’t so much the physical side of filming which was difficult - you just get on with it - it was having the mental stamina to deal with the cold and the rain. It was pretty intense. People were offering blankets and tea and we were loath to take them because, in a strange way, all of that cold and discomfort really, really helps the performance.

“When I was in all of them, they were very long days. But I quite like throwing myself into things and if you’re prepared and you turn up on time and learn the lines for all the scenes that day then you shouldn’t really have a problem. The only time I struggled was on one particular scene where we all had to do press-ups and Jack, as the leader of his platoon, has to do press-ups to the last while everyone falls down around him. It meant that some people would do two press-ups in a take and then fall down, some people would do five and then fall down, some would maybe get up to ten…but I had to do about 20 each take! I know that doesn’t sound like a lot but after 10 or so takes your arms are absolutely wrecked.”

“I love the birthday party scene where Rudyard tells an audience of children a story. The extras weren’t all that interested in what David was saying because whenever Daniel (Radcliffe) walked in, all the kids were just fighting the urge to look at him. But Kim and I were grinning like idiots because David has such an amazing story-telling voice - it was magical."

“It felt eerie filming at Bateman’s. Sometimes you’d think ‘do they actually approve of what we are doing?’ And would they be happy with the way their story is being told?’ I remember at one point Daniel grabbed my hand and took me to the house where, in the archway, all four of them had etched their names into the stone. I almost burst into tears."