As any Hollywood director will tell you, finding the perfect match to play the protagonist in your film can be a notoriously time-consuming and frustrating procedure. First you have to hold auditions, separating the few grains of wheat from an often wide field of chaff. Then once you've found a star, you have to deal with their money-hungry agents and the non-stop demands of Hollywood's elite.
But when you are filming without permission in one of the most dangerous places on earth, such trials are the least of your concerns.
When Benjamin Gilmour arrived in Pakistan four years ago to begin shooting his first film, the most pressing thing on his mind was finding a way into Pakistan's lawless tribal lands that would not result in him being shot by either the fierce Pashtun tribesmen who live there or by the myriad of Taliban fighters, Pakistani secret service agents and unmanned Predator drones that have turned the rugged mountains on the Afghan border into one of the most violent corners of the world.
Finding good actors actually proved remarkably easy. "To have a proper casting we would have needed proper auditions, but because we were shooting in secret we couldn't do that," recalls Gilmour, who when not gallivanting around the foothills of the Hindu Kush can be found driving an ambulance in his home town of Sydney. "So when I found a man who was willing to give me the protection of his clan, he also suggested that the only way we'd be able to recruit actors was from within his own family." The only exception to that rule was casting the main role, which was filled by a former mujahideen fighter from the Afghan war against the Soviets called Sher Alam Miskeen Ustad.
"He'd only ever seen one film in his life and that was Rambo III," recalls Gilmour, chuckling at the thought of a mujahid warrior watching Sylvester Stallone charge around Afghanistan battling Soviet gunships. "The CIA used to show it to the Afghans to try and get them to sign up to the war. And yet Sher Alam's performance is so subtle and on the money, it's remarkable."
The result of this somewhat improbable casting procedure is Son of a Lion, a film shot for little more than £2,000 which has gained widespread praise at this year's film festivals and is currently on limited cinema release across the UK.
The film tells the story of Niaz, a young boy growing up alongside his father in Darra Adam Khel, a dusty bazaar town to the south of Peshawar which is renowned for its talented gunsmiths. The boy's father, played by Sher Alam, wants his son to continue working in his gun shop, but Niaz is determined to go to school.
The film is so unusual because it is shot in the region where it is set, a place that has long been deeply mistrustful of outsiders and, since the September 11 attacks, has been at the centre of America's so-called war on terror. Few filmmakers have spent much time there, and most of those that do only enter with an army escort. Gilmour went in on his own, relying instead on pashtunwali, the complicated tribal code used by Pashtuns which dictate that a guest who is invited in must be given the full protection of the tribe – be they an Australian paramedic turned filmed director such as Gilmour, or an internationally wanted terrorist like Osama bin Laden.
It was while working in London as a nurse on the set of popular televisions shows such as The Bill and Murphy's Law that the 34-year-old Australian first began to think about a career change.
"Being a unit nurse on a film set was rather tedious for an ex-frontline paramedic but it meant I got to spend a lot of time in Winnebagos working on my script. And it gave me an insight into film-making which I didn't know much about before."
The Pashtuns of Pakistan were never far from his mind. On his way to London, Gilmour had travelled through Asia, arriving in Darra Adam Khel in August 2001 at a time when the gun bazaar was still recommended in the Lonely Planet as a must-see for adventurous backpackers who wanted to know what it felt like to fire an AK-47. Gilmour instantly fell in love with the Pashtun way. "When you spend time with ethnic Pashtuns you just realise how much they have over us in terms of hospitality and generosity," he says. "They're very good-natured people with a great sense of humour."
A month later the September 11 attacks happened, shining an uncomfortable spotlight on the Pashtuns, a portion of whom produced the Taliban and still give sanctuary to Bin Laden's al-Qa'ida.
Gilmour decided that he wanted to make a film which would tell the outside world about the ordinary lives of the Pashtuns.
"The general media depiction of the Pashtuns after the fall of the Taliban disturbed me greatly because it bought in to all the stereotypes," he says. "I wanted to stick up for these people who I had befriended and who had befriended me."
In 2005 he moved to Lahore, grew a beard and, without the permission of the Pakistani government, began long and convoluted discussions with leaders from the Afridi and Shinwari tribes, seeking their protection.
"Once they considered me a friend and they were aware of my agenda – that I was there to help bring their voice to the world – they got on board one hundred per cent," he says.
Shooting the film, however, was still dangerous. "It's a very hairy place, crawling with secret service agents. I was lucky to get out the first time, let alone the second."
But living with the Pashtuns has also immersed Gilmour in global politics. He is convinced that military incursions into the tribal area by the Pakistani army and missile attacks by America's drones will do little to wrestle this area away from the militants. "We're never going to be able to encourage Pashtuns to embrace modernity and democracy by force," he says. "At the moment Pashtuns are pawns in their own development, they're so frustrated by that. They want to move forward and progress, but they're being inhibited by constant war which pushes their youth towards radicalism."