The walking MP

Rory Stewart has trekked about 9,600 kilometres across Asia; at 28, wrote a bestselling book, The Places in Between, about the walk; was governor of a province in Iraq at 29; and last year, as well as becoming a Harvard professor, was hailed by Esquire magazine as one of the 75 most influential people of the 21st century.

Brad Pitt has already bought the rights to his biopic. And he is only 36. Now the former British diplomat described by The New York Times once as "living one of the most remarkable lives on record" has been selected for the safe Conservative seat of Penrith and the Border.

Stewart wants to buy a home in the middle of the constituency — the largest in Britain — so that he can reach anywhere within a day by foot. He is tickled by my suggestion that he might become known as "The Walking MP". We meet in a west London café. Dressed in an immaculate suit and silk tie, Stewart is unfailingly polite and mentally spry.

When Stewart met David Cameron and told him he wanted to stand, he was "polite but neutral. He advised me to think it through very carefully." Like Cameron, Stewart is an Old Etonian but he is quick to deny accusations he is joining an old boys' club. "I wasn't at school at the same time as anyone in the [shadow] Cabinet. I have no network."

Stewart is best-known for his epic solo walk. From 2000 to 2002, he took in Pakistan, Iran, Afghanistan and India. "I'm really bad at explaining why I did it," he says now. "I had a lot of romantic notions about what it would mean to cross Asia by foot." The walk included an about-650-kilometre trek in mid-winter from Herat to Kabul in the days after the fall of the Taliban. The experience helped him set up the Turquoise Mountain Foundation, a charity that helps regenerate Afghanistan by teaching crafts to locals. His unique insight also means that he is a regular consultant on Afghanistan to Hillary Clinton and the United States special envoy Richard Holbrooke. Does he wonder why he is never called upon by the British? "Ninety per cent of the troops are American," he shrugs. "They're the ones who wake up at 2am worrying about whether they're doing the right thing. Brown's approach is much more complicated. He is thinking about how this or that decision will play with the Obama administration, the army, the public, the media."

It is Stewart's belief that the Conservatives will find it much easier to deal with the Obama administration. "Brown is seen as a lame duck in the US, and people in Washington aren't interested in talking to him."

Once on the back benches, Stewart will argue for a major rethink on intervention. "Rebuilding Afghanistan, even to the level of Pakistan, would take 30 years of huge investment. And why should we commit? Al Qaida are internationally focused, educated, middle-class Arabs. They are not in Afghanistan. The CIA is almost certain Osama Bin Laden is in Pakistan. And if it is poverty we are worried about, we should be in Africa.

We need to step back and take a good look at a map of the world and realise there are more important places to focus on. I'm not saying we should withdraw completely from Afghanistan as we did in the 1980s," he says, "but neither should we create a massive unstable edifice we can't afford to maintain. We are about to create an Afghan army made up of 450,000 troops: This is four times the size of the British Army and would cost more than $2 or $3 billion a year to maintain. The annual revenue of the Afghan government is $600 million so this would be 500 per cent of their revenue. In Britain we spent 10 per cent on ours and their population is half the size. And who do you think is going to end up paying for it?"

Stewart speaks elegantly in perfect, to-the-point paragraphs. He once told a former colleague that he added "ums" and "ers" to his speech at school because he was scaring the other children. He speaks Persian, Dari, Urdu, Nepalese, Serbo-Croat, Indonesian, French, Greek and Russian.

At Harvard, where he was director of the Carr Centre for Human Rights, his lectures on "War, States and Intervention" were so popular that students would sit on the floor to hear him speak.

Born in Hong Kong to a former diplomat and his academic wife, Stewart describes his childhood as "idyllic", a fact for which he credits his father, who is 50 years his senior. "We lived in London when I was very young and he would wake up at six every morning and teach me fencing in Hyde Park before taking me to school. When my father was posted to Malaysia, we would take sandwiches in our backpacks and go hiking in the jungle or make bamboo rafts to sail down rivers."

After Eton, he joined the Black Watch for a year. Finding army life "not as interesting or glamorous" as he had hoped, he left to study history and philosophy at Oxford. Fast-tracked through the Foreign Office, he was posted to Indonesia in late 1997, just before the country's economic collapse. It is hard not to wonder whether someone so accustomed to such adventure might find life as an MP tedious.

Apart from political ambitions, Stewart has other, more personal reasons for coming home. "I want to ‘normalise' myself," he says. "I would love to have a family. But that's jumping the gun." He gives a thin smile. "I'd like to find a girlfriend." He hasn't, he says, been in a serious relationship for over seven years. As we leave the café, the mood dims. "I have planted over 6,000 trees at home in Scotland, some of them oak. I'd like my children to be able to watch them grow."