Rory Stewart, I presume

A chilly spring evening in Kabul. On a hill in the southwest of the city is a mud-walled fort. Behind its high walls are a series of courtyards, corridors with traditional wooden carved panels and ornate shelving in moulded clay. In the central courtyard is a judas tree, an arghawan in the local language of Dari, a dialect of Persian. Rory Stewart, in black brogues, blue striped shirt and slate blue-grey suit, is talking about the tree. Soon it will blossom, he says, and he quotes a couplet composed by the 16th-century Mughal emperor Babur.

Stewart - author, traveller, adventurer, former deputy governor of a chunk of Iraq, erstwhile tutor to the heirs to the British throne, sometime adviser to the great and the good and the powerful, current Ryan professor of human rights at Harvard, 36 years old - has just stepped off a plane. Twelve hours from Boston to Dubai, two-and-a-half-hours to Kabul, then the Afghan capital's traffic. Now he stands in the calm of the buildings that, without him and Prince Charles and a number of other major donors, would have crumbled or been bulldozed long ago. A small cluster of people who work at the Turquoise Mountain Foundation, the NGO Stewart runs, has formed around him on the fort's lawn. A peacock struts past. Stewart searches for more cups for more pale-straw coloured tea from the communal kitchen. The cluster disperses and I walk over and say hello. Stewart greets me Afghan style, with a shoulder to shoulder half embrace, pleasantries and the quote from the Emperor Babur about the judas tree.

A century and a half ago there would have been nothing unusual about Rory Stewart. The empire was full of Eton and Oxford-educated sons of Scottish civil servants who spoke several exotic foreign languages, knew how to eat rice with their fingers, could talk for hours about local architecture or crops or religious practices, and ask questions such as, "Do you think Sher Mohammed Akhunzada or Gul Agha Sherzai did a better job as governor of Kandahar?"

But Britain, indeed the west, does not do people like Rory Stewart very much these days. In the morning, Stewart suggests we go for a walk. In all the dozens of times I have visited Kabul, I have never walked the remnants of the old city wall. For a long time it was dangerous, laced with mines or simply too far away from habitation to be secure. But even in these nervous days the walk, Stewart tells me, is relatively safe. The wall lines the crest of a steep hill on the southern rim of the old city of Kabul. From its top you can see north to the still snow-covered Hindu Kush, east past the airport and the huge Nato bases, and south to the provinces currently half under insurgent control.

We are dropped off at the foot of the Bala Hissar, the old city castle, currently an Afghan army base with American-supplied Humvee semi-armoured cars lined up on its parade ground.

It is Nowruz, the Persian new year, and the people of Kabul have thronged to the muddy, rubbish-strewn lakeside underneath the ruins of the fort. Women in blue burqas pick their way in 2in white stilettos through the muck. Children scrap noisily around the battered, rusty swings. A hawker offers dusty dried figs, popcorn, rubber bands. Sheep scatter as two young men on a Chinese motorbike ride too fast through the crowds. The whole scene is overseen by heavily armed police on the lookout for alcohol and suicide bombers.

Since the early days of the arrival of the west in Afghanistan in the aftermath of the 2001 war, few of the tens of thousands of foreigners stationed at any one time in the country have spent much time walking. The United Nations expats stay in their white Land Cruisers, the diplomats only move with their close protection teams. Paradoxically, those best capable of defending themselves, the soldiers, never mix with the population. Barricaded behind treble lines of wire and blast walls, which have multiplied every time I have returned to Kabul since 2001, many serve their entire tours without talking to an Afghan or eating an Afghan meal. So as Stewart and I walk, people look. With interest, curiosity, without hostility.

The evening before, Stewart had told me that, driving in from the airport, he also noticed the lack of any foreigners, military or civilian, on the streets. It was a glimpse of what Afghanistan might look like without foreigners at all. This is Stewart's big, angry argument. It is one that he has made vocally, in British newspapers, to Hillary Clinton when invited to dinner with the new American Secretary of State, to Richard Holbrooke, the new special envoy to the region appointed recently by President Obama, who has brought Stewart on to his bench of advisers. Stewart argues that, just as the west is gearing up to perhaps double the number of troops in Afghanistan, we should be doing the opposite and getting the troops out. We are not doing any good, Stewart says. More troops means more fighting, which means more civilian casualties and violence and more people hating us and what we stand for. We need an Afghan solution for an Afghan problem. It is not a view that has made him very popular.

And so we walk. I am gasping in the thin and polluted mountain air of Kabul. Stewart is apparently unbothered. It was walking that made him famous, or at least writing about walking. After a year as an infantry officer, followed by Oxford University and then three years with the Foreign Office in Indonesia and Montenegro, Stewart resigned to walk across Asia. "It wasn't very serious. It was just an adventure," he says, adding that, after years "in embassies" he was deeply curious about "rural life". It took 18 months. He crossed Iran, Pakistan and was halfway across Nepal when he heard that the Taliban had fallen.

So he retraced his steps and walked from the western Afghan city of Herat across the impossibly remote central Afghan highlands to Kabul in the thick of winter, staying with local people all the way. It was an insane thing to do, the sort of exploit few travel writers bother with these days - dangerous, improbable and gruelling. The Places in Between, a finely written account of the trip, full of dry humour and detailed observation, was an international bestseller.

In 2004 Stewart was appointed deputy governor of Iraq's Maysan Province, trying to fashion some order out of the chaos of post-Saddam Iraq. "I naively thought that I could do some good, that I might have some skills that could be useful," he says. Stewart's 12 months in Iraq, spending wads of American dollars delivered in plastic-wrapped blocks of $10m to his offices, culminated in a terrifying firefight as local militia bombarded his administrative office and resulted in a second book, Occupational Hazards which, though full of the same humour and irony, is darker, more acerbic and disillusioned than his first. "I learnt how little you could do in a country where people had a strong idea of what they wanted for themselves and where there was a strong and developed mass politics," he says. "I was working hard and I hoped for them, but they weren't interested."

This too has become a crucial component of Stewart's controversial credo: that western efforts at nation-building are bound to fail in the face of politically conscious, historically aware populations. "The British couldn't do it in Iraq [90 years ago], even with highly trained Arabists who spent years in the country and a rural and illiterate population," he says. "Now, people know what they want and they don't want us to do it for them, or tell them what is in their best interests or otherwise."

A year's writing fellowship at Harvard followed, and then a call from an old contact: Prince Charles. And this is where the already slightly outlandish world of Rory Stewart becomes slightly surreal. The connection with the royal family, Stewart says, is very simple. A prefect at Eton, Stewart ended up sitting next to the prince at a dinner, impressed him and was asked to tutor Harry and William at Balmoral one summer. "They were 11 and eight and not very interested. I was a crap teacher and they were on summer holidays and probably would have preferred shooting rabbits or whatever," Stewart remembers. But when Stewart was in Iraq, the prince contacted him to suggest setting up a carpentry school in the rough southern town of Nasiriyah. Initially sceptical, Stewart contacted the head of the local labour union, out of work following the dissolution of all unions by the new American pro-consul running Iraq at the time, and gave him some money. To Stewart's surprise, when he returned six weeks later he found a workshop full of hundreds of street kids learning joinery on brand new machines.

Which meant that when the prince contacted him again about scouting a location for a traditional school of arts and crafts in Kabul, he went. "My gut instinct was that the Afghans probably needed plumbers and electricians more than calligraphers or carvers, but I thought I'd go and look," he says. The Turquoise Mountain Foundation, named after a lost Afghan civilisation, is the result.

On a rainy morning, I walk round the classrooms that have been built around the fort, as what will be the main school is being restored. There are 132 students, who all do three years at the centre. They are paid a stipend and competition for the places is predictably tough. Get one and you get not just a craft - calligraphy, jewellery, woodworking, pottery or miniature painting - but literacy lessons if needed, English tuition and IT classes.

It is an astonishing project. In a bustling workshop, some of Afghanistan's finest master craftsmen - taxi drivers or fruitsellers a few years ago, despite their talent - teach a new generation traditional skills that were in danger of dying out. The wood-working faculty is so successful that it pays its own way, fulfilling major commissions for universities, embassies and British luxury hotels. Fundraising was a nightmare and managing a shoestring project fun but extremely stressful, Stewart says. When the seed cash raised by Prince Charles from a celebrity dinner in 2005 looked like it was running out, Stewart started travelling, cajoling, talking, persuading, giving presentations from California to Kuwait. The money finally started coming, and now major international donors have guaranteed cash for the project for the next two years. The next step is to set up a trust fund to assure funding for the next 30. The project's operating costs are currently around £500,000, about what it costs to keep two expats at the British embassy for a year (not including the salary).

The walls of the city peter out in narrow alleys between stone and mud homes, few of which have sanitation and even fewer electricity. We drop down to a dirt road and the gardens of Babur. The tomb of the Mughal emperor and the formal gardens around it suffered badly in the civil war between mujahideen factions of the early 90s, but through aid from the German government and the Aga Khan, they have been rebuilt. On this New Year's Day they are very busy. Families picnic beneath blossoming trees - chinar, arghawan, almond, walnut, apricot, pomegranate and peach. Teenage boys swagger in stonewashed multi-pocketed jeans and shiny nylon shirts. Young women made up like Persian miniatures walk by in yellow, green or purple veils, and shawls covered in gold and silver sequins. Card players roar with laughter. Children run rings around a radio and tease a smiling greybeard who claps with palsied hands.

The fort and its school are only part of the Turquoise Mountain Foundation. There is something much more ambitious under way. From the city wall, we looked down on Kabul.

I recognised the football stadium where I had watched executions under the Taliban. Down by the river, in the centre of town, Stewart pointed out a triangle of jumbled, flat-roofed, mud-coloured buildings. That, he said, is Murad Khane. Murad Khane was a slum area set back from the main square of Kabul's centre, of no particular interest to anyone for a long time. Town planners from Berlin and Moscow had hoped to raze it and rehouse its poor inhabitants in tower blocks. War and geopolitics stopped the demolition but also left the 600-odd families of Murad Khane mired in deep poverty.

It is still not exactly Knightsbridge. It is a poor neighbourhood in a country where the average life expectancy is 43. But things are better than they have been for years. Stewart arrives in Murad Khane and is greeted by the foundation's chief engineer, a boisterous and highly competent Kabuli. A walk down the narrow lane beside the mosque, which is the most significant thoroughfare - lined by sellers of lapis lazuli jewellery, bakers with discs of flat bread nailed to their shop fronts, the air filled with smoke, shouting, fumes from Kabul's atrocious traffic - is almost regal: Stewart's hand is taken and shaken a dozen times.

We walk past a small courtyard, recently cleared of debris accumulated over decades. "Wasn't done last time I was here, excellent," nods Stewart. It is easy to mock. And plenty do. Stewart's ambitious project in Murad Khane - the aim is to restore a whole series of buildings as a national centre for traditional arts while simultaneously regenerating the entire area through a range of community outreach projects, including a school, a clinic, a women's bathhouse, paving, electricity, water and sanitation - has provoked press reports of the "toff in the slums" type. This clearly irritates Stewart intensely. He does have more Eton in his accent than his native Perthshire, and there is an element of provocation in the long jacket and the brown leather boots. And he is not trained in urban regeneration or archaeology or even conservation - "Half our battles in the early years were against the snobbery of international experts who saw us as incompetent amateurs," he says. There are those, too, who say that he is creating a Disneyland Afghanistan. "I'd have more sympathy for those who criticise the project if they were out creating mini-utopia all over Kabul. But they are not," snaps Stewart.

A few days before seeing Stewart, I visited Abdul Ahad Sahibi, the mayor of Kabul, who wants to widen a road next to Murad Khane, slicing between three and six metres out of the area that Stewart is so carefully restoring. Sahibi says Murad Khane is on municipal land, that there are legal issues and that Afghans do not want a museum but nice, clean concrete apartments. "That's not what we hear from the community," says Stewart. "They have lived in these houses for generations. They want all the comfort and convenience, of course, but if they can have it while keeping their homes then they are even happier."

We are standing in the courtyard of a magnificently restored house from the Kabul of the 1880s. One of the first things Stewart organised in Murad Khane was the removal of caked layers of rubbish which had, over decades, filled in entire streets. Men from Murad Khane have been hired as labourers, others have now moved from handling a spade to handling fine woodwork tools after serving an apprenticeship at the foundation. As it is Nowruz, there is a feast, with speeches, a circus and schoolchildren in spanking new uniforms singing songs about education and the national Afghan anthem.

Earlier I asked whom Stewart would have been had he been born 150 years earlier. David Livingstone, the explorer, he says, and then quickly starts talking about Alexander Burns, a young British diplomat whose meteoric rise ended in his death at the hands of a Kabuli mob only a mile or so from where we are standing in 1841. And then about Lawrence of Arabia, describing how Lawrence was rejected by the establishment. "That's what the establishment does," Stewart says. "It destroys you." There is a bitterness in Stewart that was not there a few years ago. He names a diplomat who called him, he says, "a snake oil salesman, a hypocrite, an ingrate", speaks of others who said he was "traumatised by Iraq" when he predicted violent chaos in the south of Afghanistan if the UK sent troops there. And he quotes from memory a passage from Rudyard Kipling's letter to Lawrence after the latter had been effectively declared persona non grata by the British government for "getting too close to the Arabs" in 1919: "But you will not go out of the game - except for the necessary minute to step aside and vomit. You are young, and the bulk of the men now in charge are 'old, cold and of intolerable entrails' and a lot of 'em will be dropping out soon." It must have been nice to get the support of Kipling, Stewart says, with a grimace, but Lawrence knew he had lost.

There are signs that Stewart's weird and wonderful world may shrink temporarily. He is still surreally well-connected, mentioning an email he has just received from a former head of MI6 asking who will win the Afghan elections, leaving me to head for a meeting with a cabinet minister. And he is still travelling. But he now owns a washing machine for the first time in his life and has a mortgage on a house bought near to his new office at Harvard. He bought at the wrong time, so Stewart can now add negative equity to the slightly more exotic perils of his existence up to this point.

He enjoys America, he says, waxing lyrical about an evening in New York, a restaurant, a girl. But it seems unlikely that academe and US property prices will ground him for long. After leaving him I search for the letter Kipling wrote to Lawrence. Kipling, the imperialist and militarist, had lost his son in the first world war. Lawrence was tortured by the knowledge that the promises he had made to the Arab tribes of what was soon to become Iraq would be broken.

As I read in my guesthouse room, helicopters fly low over Kabul. Tomorrow, Stewart will be in Murad Khane and I will be heading off to spend a week with the American army in an insurgency-ridden province to the south. "We are all sitting in the middle of wrecked hope and broken dreams," Kipling wrote, 90 years ago.