The Reluctant Hero

"I'm absolutely not a heroic figure. I'm a comic figure," he says, as the news emerged that Orlando Bloom – as handsome and heroic-looking as movie stars can get – is the person behind this project and also planning to take the lead role. The English actor, who built his fan base as Legolas in Lord of the Rings, proposes to play a man who used his experience as the deputy governor of Iraq's Dhi Qar province to expose what he believed was intrinsically wrong there.

"I might be better played by Danny DeVito," Stewart modestly suggests.

"I think these kinds of things can be approached quite well through comedy," he goes on, "because one of the good things about the Ealing comedies is that the great, imperial ambitions of the 1950s had a darkly surreal, illogical nature. I'd be interested in trying to get that across."

The Eton-educated Stewart is undoubtedly a romantic figure; he would be well-placed as a Scottish hero on film. From Oxford University, he served a year in the Black Watch. He later worked as a tutor to Princes William and Harry and served in the Foreign Office, including a stint in Indonesia. He has been made OBE and heads a charity that aims to improve lives in war-ravaged Afghanistan.

He wrote his first book, The Places in Between, based on his walk across Afghanistan, crossing snow-filled passes, staying as an unwilling guest of the Taleban and being beaten up at a Kabul checkpoint.

Then he turned up in Iraq and signed up with the Coalition Provision Authority, serving in senior positions in two provinces there. That experience was the basis for his next book, The Prince of the Marshes: And Other Occupational Hazards of a Year in Iraq. About two weeks ago Bloom turned up in Perthshire, where Stewart's family has its home, after a visit to the Edinburgh Festival. The two men went walking through the glen, down into Crieff. It was the second time they had met in Scotland; Bloom also came to listen to Stewart speak publicly about his charity, the Turquoise Mountain Foundation, and it was supposedly this first encounter that inspired Bloom to film Stewart's story.

The film project now emerging is to be scripted by the Irish novelist Ronan Bennett and is said to focus on three stages of Stewart's life: his travels on foot through Afghanistan; his work at the Foreign Office; and his aid work in Kabul.

Turquoise Mountain, which Stewart launched single-handedly two years ago, now has some 350 employees and appears to be his main focus. He proudly lists its achievements: clearing 11,000 truckfuls of garbage from the old city of Kabul, restoring some 50 buildings, setting up clinics, primary schools, programmes to establish women in trades and exporting and marketing their products abroad.

Stewart is reluctant to discuss the film. It's a "very early-stage thing", he insists. "We haven't got as far as signing a contract …

"I'm a bit ambivalent about it. I think what my books are really about is my sense, in Afghanistan, of what culture outside Kabul seems to be like for a foreigner, and in Iraq to talk about why the coalition was so unsuccessful and the project so doomed.

"I try to keep myself out of the books, I don't talk about my own personality or life. I'm not quite sure how this could work."

However, "if it was something that was able to draw attention to the work of the charity in Kabul, it would be exciting."

His own role in Iraq is rather like "a bit part in The Office", he says.

"What you notice working in these countries is the amazing jargon of bureaucracies, the water-cooler politics. If you were able to convey that (in a film], get over a culture of PowerPoint presentation, you would begin to show an audience why something could be a catastrophe, without reducing it to saying everyone there is evil, or stealing money, or stupid."