Roz Laws speaks to director Ken Loach about soldiers for hire and the horror of water-boarding for his latest film.

For much of our conversation, he comes across as a softly spoken, polite pensioner.

But, while he’s certainly not an angry young man any more, Ken Loach can still get quite worked up about things.

Such as when he’s discussing the CIA practice of water-boarding – and explaining how his quest for realism in a torture scene left one actor suffering panic attacks and nightmares.

Loach’s latest film, Route Irish, concerns the use of private contracting firms in Iraq.

Mark Womack and comedian John Bishop play Fergus and Frankie, best friends from Liverpool who become mercenaries in Baghdad. When Frankie is killed, Fergus sets out to discover what happened to him.

And to get the truth out of another private soldier, played by Trevor Williams, he water-boards him in an intensely realistic and disturbing scene.

Water-boarding involves pouring water over the face of a victim, whose face is usually covered by a cloth, so they think they are drowning. The technique can cause physical injuries, lasting psychological damage and even death.

“It’s a pivotal scene,” explains Warwickshire-born Loach. “We made a mask that fitted over Trevor’s face to protect him from the water and experimented with a tube coming out of his mouth so he could breathe.

“But none of it worked, we had to cut every time we got to the point where we put the mask on and it lost the tension.

“After a bit, Trevor said ‘To hell with it, let’s do it’. It was very brave of him to agree to actually be water-boarded.

“After every take, we asked him if he was all right. He was free to sit up, he wasn’t strapped down as he would be as a real captive. Trevor got through it and afterwards he said he was fine.

“But on his journey home to Manchester, he had a panic attack on the train and he didn’t know where he was. He said he could feel the cloth on his face. He had horrific nightmares for the next couple of weeks.

“That was in a situation where he knew it was acting. Imagine really being tortured, it would be terrifying. It was important to do that scene and Trevor was committed to it. He’s fine now.”

President Barack Obama banned the use of water-boarding in 2009 but Loach believes it still goes on.

“It’s been done in our name and we haven’t disassociated ourselves from it,” he says. “The irony is that you don’t hear the truth from suspects who are water-boarded. People will say anything to make it stop.”

Loach grew up in Nuneaton as the grandson of a miner and son of an electrician. A grammar school education led him to a law degree at Oxford but his heart lay in the arts.

He has had the urge to make films highlighting social issues from his ground-breaking 1966 TV play Cathy Come Home. The miners’ strike, the Irish Troubles, labour rights, disaffected youth and immigration have all been subjects for his work.

In Route Irish, he turns his attention to the use of private soldiers in Iraq, which hit the headlines in 2007 when the American firm Blackwater Security killed 17 civilians in Baghdad.

He says: “The privatisation of war is pretty serious and has crept up on us. All the films about Iraq ignore it.

“It follows the current politics of selling everything off, and here we are doing it with war. If you privatise it, you hide it. There are no politicians weeping crocodile tears when a contractor dies, there’s no political pressure to end it.”

Route Irish is riddled with swear words and I wonder if he thinks the profanity is overdone.