Paddy Ashdown is a good bag carrier. His made-in-the-Royal-Marines physique allows him to pick up my suitcase and lope effortlessly between armoured car, airport lounge, plane, bus and every other staging post on our journey. Not that we are supposed to be on a journey. We are meant to be installed in tan leather armchairs in the penthouse office in Sarajevo where the Lord Ashdown of Norton-sub-Hamdon, high representative for Bosnia and Herzegovina, exercises powers equivalent to those of the Red Queen in Alice in Wonderland. But that was before the crisis.
Ashdown had been on the brink of a deal integrating the Serbian, Croatian and Muslim armies that fought the 1992-95 war, obliging the forces responsible for 250,000 deaths to wear identical uniform and swear the same oath of allegiance. Then came a late attempt by the Bosniak state president to block the proposals, followed by an ultimatum from Ashdown. No agreement, no chance of getting into Nato. That warning delivered, he began the attempt to salvage his battered defence initiative.
Hours pass before he emerges, yawning, and late for an evening summit in Geneva. We have already agreed that we will talk on the way. "Crises are ten to the buck here," he says. "It is exhausting and carpet-chewingly frustrating at times. If you like taking decisions and living with the puzzle of crisis, this is good fun as long as your energy lasts. My time is up in May, though I might go on a bit longer if I'm asked. I love this country - muddled, dysfunctional, but with people I really admire, although I could be a bit less kind about their politicians. I've led the Liberal Democrats, which, apart from being prime minister, is the job I would most have liked in the world. And then I was asked to build a state."
In other ways, life has been less blessed for Ashdown, who never cajoled Tony Blair into forging a new centre-left alliance or adopting proportional representation. Yet world events have decreed that the fourth, and easily the most hyperactive, high representative for BiH has become a quietly powerful figure, consulted by the US secretaries of state and defence. Ashdown, the benevolent despot charged with conducting the first western experiment in nation-building since the cold war, may have lessons for Iraq. Colin Powell and Donald Rumsfeld are watching and listening.
Ashdown is still tapping into Westminster affairs. Later, he tells me what he thinks of his successor, Charles Kennedy, and why Blair has permanently squandered his chance of greatness. But we begin with Ashdown's fiefdom. Superficially, Sarajevo has been transformed in a decade. A marbled airport has replaced the battered airstrip where Hercules transporters disgorged visiting politicians and journalists into tanks shuttling to the city; fountains play beside the main thoroughfare, still known as "Sniper's Alley". It is safe. A million refugees have come home.
But Sarajevo is oddly unchanged, too. Although the roadside posters show women in black hold-up stockings, there are few international high street franchises, apart from Benetton, whose war-and-woollies advertising fitted the Bosnia brand. The time when a black-market lipstick cost £25 and a hospital anaesthetist earned 27p a week is gone. But prime ministers still get £8,000 a year, the economy creaks, corruption thrives, and half the population lives on or below the poverty line.
Across the River Miljacka from Ashdown's office, an acne of bullet holes in brick blocks of flats evokes how things were in the days of ethnic conflict and how, gloomier citizens think, they may be again if foreign troops pull out. Ashdown is not so pessimistic about his diffuse empire. He is, however, faintly embarrassed by his power. The upholder of the Dayton Peace Agreement may (and does) fire prime ministers or judges with impunity.
Can a liberal democracy capable of joining the EU as soon as 2009 really be built on the mandate of a Victorian colonial administrator? "Good question. The answer is that it can't, not permanently. Getting rid of my job is within my remit. By the time I leave, I want this job finished, and I think we're on track for that. We have moved from pretty heavyweight use of the powers to more of a partnership."
But the European Stability Initiative, a think-tank on Balkan affairs, recently accused Ashdown of running a "European Raj". "I thought it was wrong and curiously dilettante of them not to do their homework. They never even bothered to come out here and see that we were already doing almost all the things they suggested. They were, however, asking a legitimate question. When will it end? It is a question I ask myself every day and one that, in the next few months, I will have to answer. If we don't answer it, then we will turn into a colonialist power."
Rumsfeld, a famously lukewarm nation-builder and one of Ashdown's paymasters (the US provides roughly one-fifth of outside support to BiH, compared with the EU's half), is eager to hear of progress on the withdrawal strategy that Ashdown calls "a white-dot plan, because it's the last thing you see on the television". Has Ashdown ever been to Iraq? "No, but Rumsfeld asked if I would go to Baghdad. For some time, there was a discussion about how I could fly out to give them any thoughts I had. In the end, I couldn't leave Bosnia for long enough." I ask how Rumsfeld behaved in the aftermath of war, and Ashdown suggests a subdued edge to the old neo-con bravado. "Our conversation was private, but he was very thoughtful - thinking about how to construct peace. Arguably, he should have been thinking about that long ago. Maybe he was."
Was he opposed to the Iraq war? "You will forgive me, Mary. To answer that is beyond my pay grade. If I was a politician, I would give you an opinion. But I am an international civil servant, and I have to hold together a coalition who provide me with money and resources. If I commented, it would interfere with my job here." But the silence of Ashdown, a vocal liberal interventionist who berated the west for not acting earlier in Bosnia and Kosovo, implies little gusto for Blair's and Bush's war.
As for salvaging peace in Iraq, he offers three vital conditions. "Be tough at the start. We got it wrong in BiH. We were too relaxed. Make the rule of law the first issue. We got it wrong in BiH by making democracy the first one. The third mistake was to come in and say it would be over in a year. It never is. Unless you're prepared to devote the same amount of time and energy to peacekeeping as to war fighting, you're going to come a cropper. Further than that I ain't going." But the errors he warns of are all being replicated in Iraq. "Who am I to say? I couldn't possibly comment." He does concede, however, that building peace in Iraq will now be "very, very, very tough".
Two weeks earlier, he had joined Bill Clinton to commemorate the thousands massacred in 1995 at Srebrenica, a United Nations safe haven. Ashdown is not an advocate for UN control. "Here I am going to be contentious. Certainly, my Liberal Democrat colleagues at home may not take the same view. My model, the Bosnian one, is a coalition of the willing. They fought the war, and they are my board of governors for the peace. Kosovo [by contrast] is a UN operation and subject to what I call the 5,000-mile screwdriver - micromanagement from New York. Which would I prefer, and which is the better system? Mine, rather than Kosovo's. The modern UN should be the repository of international law and the legitimiser of international action. But the UN is not a good management organisation for doing things."
By now, we are in an airline VIP lounge, under the gaze of one of his five bodyguards. Ashdown eats a crisp to compensate for his missed lunch, and smokes a Marlboro Light. At 62, he finds Sarajevo more gruelling than Westminster. "In a strange way, I think it's more remorseless. I'm getting older, and that is one of the problems. For the first time in my life, I feel my energy doesn't outrun the job. Here, I have to be right every time. These huge powers don't mean I can blunder around. I have to gauge public reaction, sometimes in defiance of elected politicians. Do not imagine that it is not exceedingly frightening to have such enormous powers in a country you know so little about. It keeps me awake at night."
Once, the dithering of Blair and the future of the Lib Dems were his recipe for insomnia. Now he is the beneficent elder statesman. I tell him that Charles Kennedy revealed, after the party's triumph at the Brent East by-election, that Ashdown had sent him a message of great praise, and he says, rather sharply: "Well, I sent it to the workers as well as Charles."
When I add that one journalist likened Ashdown's Action Man image to Kennedy's Cabbage Patch Doll, he laughs a little more uproariously than seems tactful. But that should not betoken any ill will. "I don't think I had reservations about him taking over. Charles and I are so different in personality that it's not surprising we didn't see things in the same way. The party is immensely comfortable with Charles. The great project [Ashdown's planned coalition with new Labour, complete with seats in the cabinet and proportional representation] was reaching its end. Charles allowed it to die a fairly natural death; the right strategy. If I'd continued as party leader, it would have been an increasingly uncomfortable relationship. It got a bit tetchy, though I love them all.
"My style is: fix bayonets and charge. I don't have the concept of the right time. I can never wait for it. I would always try to make [political forces] do something else. Charles's style is a good one; it shouldn't be misjudged as lazy and lacking in application."
And what of Tony Blair, who squired him practically to the altar before jilting him and deferring any centre-left alliance, as Ashdown believes, for another generation? He seems genuinely to bear no grudge, perhaps because Blair is said to have lobbied for the Bosnia posting and supported Ashdown when he was installed. Once he asked himself whether Blair would be a great prime minister, or merely good. Does he have his final answer?
"A good one, not a great one. Great prime ministers, in Roy Jenkins's phrase, change the weather. I don't think Blair has changed the weather. I like him, I admire him, I think he's done some extraordinary things." Blair's foreign policy has been successful, "leave aside Iraq, which the jury is still out on. If he had achieved Europe [euro entry], that would have made him great. Has he been one of the great 20th-century prime ministers? No. You would have to say those are Lloyd George, Thatcher, Churchill, Attlee."
So what went wrong? "He overestimates the power of his charm. It is immensely powerful, but not quite the Excalibur that can overcome all difficulties. He would always say: 'Oh, don't worry about [the anti-coalition] John Prescott. I can deal with him.'" Ashdown has a theory. Blair's problem, he believes, is that he never learnt to measure risk. "I've lived my life from quite dangerous positions, so assessing risks is something I've always done. Blair's rise was unchecked - aside from Iraq and the death of [Dr David] Kelly. If you haven't been through danger, you don't know how to assess it.
"To be a very good prime minister, you have to break the mould. He has changed the Labour Party - whether permanently or not remains to be seen. But he hasn't, in the end, changed Britain in the way he would like to have done."
So much for Tony Blair's epitaph. What of Ashdown's? That will depend, in large part, on what happens to Bosnia and Herzegovina, poised between becoming a model of 21st-century nation-building or an economic disaster fracturing down old ethnic fault lines. I found out later that Ashdown's brinkmanship on defence had worked. The armies will begin to integrate. But other crises, great and small, threaten to engulf him. Foreign investors must be found. A row over a Mostar rubbish tip must be defused.
The only constants are Ashdown's ferocious energy and desire to succeed. He puts the chances of achieving a functional liberal democracy at 80 per cent. But then he is, by his admission, ambitious. I retrieve my suitcase and watch him walk wearily across the airport, a man weighed down with other people's baggage.