Craig Murray, the former British ambassador to Uzbekistan, is in Vienna on a short break with his 23year-old partner Nadira. "I'm en route to the opera, actually, " he says down a patchy mobile phone line. "It's snowing heavily." It is difficult to understand him because the connection is so bad and his speech impediment - which he doesn't mind anyone mentioning - means he struggles to pronounce his Rs clearly.

It all sounds like something out of a cheesy chocolate advert - the ambassador, the opera, the foreign location - until he adds: "I'm back at the weekend to drive up to Blackburn. Let's meet up before that."

Little more than 72 hours later, in a west London street, the circumstances are rather different. Given that the papers say the troubled ex-ambassador was given a [pounds]315,000 pay-off when he was withdrawn from his ambassadorial post last year, it seems reasonable to expect that his address will reflect a man of means. Instead, the light outside the appointed apartment block is so low it's difficult to spot Murray's name on a plastic buzzer.

"Watch the cat, " he says quickly when he answers the intercom. "Can you grab her?"

Inside the flat, Murray's singular presence is immediately obvious. At 46, he has the pearshaped torso of a man who has spent most of his life sitting down. His thick blond hair is cut in a bowl-cut reminiscent of Keith Chegwin or Curly Watts from Coronation Street, and he has the stiff-armed walk of a career diplomat used to guiding people - without actually touching them - in the direction of their next ribbon-cutting ceremony. Although it's after eight on a Friday evening, he's still wearing a well-ironed shirt, with square gold cufflinks and a smart red tie. His shoes are expensive square-toed jobs, in soft black leather. He looks not unlike a spiffed-up bingo caller.

Then something odd occurs; he gestures with a flick of his hand to start the interview. It's when he does this that you realise this is someone whose offbeat style actually works to his advantage: what you see is not what you get. As he talks, the bingo-caller disappears and a complex and quite penetrating intellectual starts to appear in his place.

Murray has been much in the news in recent years. His story became public property in 2002 when, as British ambassador, he made a speech decrying Uzbekistan's human rights record.

Last October a memo he sent to the Foreign Office complaining that MI6 was using information from Uzbekistan obtained by torture was leaked to the press. Such outspokenness is not what you expect from a diplomat. Around Murray's claims came a swirl of murky counterclaims embroiling our man in Tashkent in sexual and financial scandals, and queries about his mental health. In the wake of the leaked memo he was suspended from his position, a bitter end to what had at one point looked a glittering diplomatic career in the making. But that will not be the end of the story. Not if Murray can help it. And the beginning? That takes us to Scotland, more or less.

"I'm an Anglo really, born in England, like Sandy Lyle and Rod Stewart, " Murray explains as we begin our conversation, "but my father came from this huge Edinburgh family. He was in the forces and was posted down to Norfolk, which is where he met my mum. I grew up down in Norfolk, but I went back up to - and always spent a lot of time in - Scotland. And as soon as I was old enough I went to university in Dundee. I did modern history."

His time in Dundee was, he says, not without incident. "They chucked me out for being a 'poor moral example' or something, " he says, laughing. "Then I came back and was elected for two years as president of the student union."

It's easy to view these details in retrospect and see signs of things that were to come. A natural rebel, Murray was also always something of a high-flier. On entering the Foreign Office in his mid-twenties, he had postings to eastern Europe and then Africa, all of which he carried out, apparently, quite brilliantly. At the surprisingly young age of 42, he was appointed to be Her Majesty's government's ambassador to Uzbekistan. And at that point his career became more of a car crash.

The buzzer sounds, andMurray rises to let in his girlfriend, Nadira Alieva, a 23-year-old native of Uzbekistan. She bounds into the book-lined living room wearing a gleaming white tracksuit and an equally glistening toothy smile. To call them the odd couple would be an understatement. He exudes a quirky gravitas, while she glows with youth and - how can I put this politely? - a vibrancy that any healthy heterosexual male would find it hard not to sense. In other words, she's pretty hot. "She's just back from a tae kwon do class, and is en route to a belly-dancing lesson, " explains Murray in a deadpan sort of way. "Where I come from, " says Alieva in heavily accented English - it's unclear whether she means geographically or philosophically - "belly-dancing is not about keeping fit but is about things cultural." Her mobile phone blasts out a rackety pop tune - "That's Britney Spears, " says

Murray - and she zips out of the room. Murray, meanwhile, segues effortlessly back into his life-story.

"At Dundee I was enjoying myself in the students' union and enjoying my social life, although I was also working very hard. I mean, I never, ever came less than first in any exam that I sat. And I ended up getting a first."

You'd assume he'd have had his career all planned out, but no. He only got into diplomacy because of a girl. "I took the standard civil service entrance exams while I was on my second year as president, and the only reason I sat them was because the girl I fancied was sitting them too, " he says. "But I had no desire to be a civil servant. To get into the fast stream of the civil service is extremely difficult, and to get into the diplomatic service is even harder.

So it didn't occur to me when I sat the exams that I had a hope in hell of succeeding.

"I passed the first bit, then I had to go down to London to a selection board over two days.

A few months after that I went back for the final selection board, and at that stage you had to say which government department you wanted to join. I looked at the list of departments and it looked really boring. Then I saw the diplomatic service. I thought, 'That sounds exciting and fun - people will talk to me at parties.'" He was later told he was in the top three for the civil service in his year.

In the background of the flat somewhere, Alieva is yelping with laughter. Two minutes later the daft Britney Spears ringtone starts all over again. Murray, meanwhile, is describing his "idealistic" student politics, and remembering how he was part of the protest against Torness nuclear power station. "I was quite radical in my own way, " he says with a smile.

Yet the man with the self-confessed radical political ideals soon found himself being promoted annually in the civil service until he was a key player on the Africa desk of the Foreign Office. By this time he'd married a fellow Dundee University student, Fiona, and a child was on the way. Things were looking up. Stints in the maritime section and Cyprus followed. He could, it seemed, do no wrong.

After the Gulf War in 1991 his stock rocketed yet further. He was sent to Poland as head of the British embassy's work on economic and political affairs, and navigated the tricky process of helping Poland enter the EU.

"Those were very good years, " he muses.

"Things were really happening. You felt progress was under way." By 1998 - under New Labour and Tony Blair - Murray was back in London as deputy head of the Foreign Office Africa section. While a natural LibDem supporter, he says he was glad to see Blair elected as PM. He was posted to Ghana, where, with his wife and two children, he lived in an opulent house but wasn't afraid to get involved at ground level: "We managed to deliver a truly democratic election in which the opposition won but took power peacefully.

I was very happy and the FO were very pleased with me and I got lots of career brownie points."

The next call he received was to ask him to be the new British ambassador to Tashkent. He accepted without even knowing where it was.

Ambassadors usually apply for jobs. It's not very glamorous. Invariably you're a timeserved diplomat from the Foreign Office whose CV reeks of the most important recommendation of all: "Has not screwed up on foreign soil." Craig Murray was such a man, and now his time had arrived. He was being appointed ambassador to Uzbekistan - not exactly a premier-division embassy, but still in the top, well, 30. For the first six months he was drilled in Russian, every day of every week. He was given facts and figures too, although nobody ever mentioned the small detail that human-rights watchdogs such as Amnesty International weren't exactly enamoured with Uzbekistan.

So, with Fiona and their children, he flew to Tashkent, the capital of Uzbekistan. He closes his eyes as he recalls his first impressions:

"Unless you've lived in a totalitarian state, it comes as a hell of a shock to see the sheer weight of the police presence. There are four policemen on every bloody street corner.

There's 40,000 armed policemen in Tashkent city. There are about the same number of plain-clothes officers from the security services too. Effectively the leadership that was there when the Soviet Union existed is still in charge. They've replaced communist ideology with nationalist ideology whilst maintaining the same power structures. It's quite fair to call it nationalist socialist, with everything that implies. It's extremely corrupt.

Officially unemployment is 0.5 per cent, but in most towns it's probably around 60 per cent."

The biggest shock was still to come, though.

"The human rights situation - just how awful it is - came home to me pretty quickly. Within a day or two I got photos on my desk of a guy who'd been boiled to death. But there was nothing about the human rights situation in my briefing before I got there. The Foreign Office talked about the importance of the US airbase strategically. Mostly they talked about the 'war on terror'. If the human rights issue got a mention, it was a mention I didn't notice."

Within a week, Murray had attended the trial of someone erroneously accused of being a political radical. "Obviously I had my own eyes opened, but also it was suddenly around town that the British ambassador had been to a dissident trial. This was a statement. Diplomats didn't do this, let alone ambassadors."

He started sending reports of human-rights abuses back to London, to which he got vague replies. So appalled was he that on October 17, 2002 - his birthday - he made a speech condemning the lack of a "functioning democracy" in the country. Although cleared by London, it still sent an unwelcome signal back home. The boat was being rocked.

Murray knew the US had about 60 CIA men on the ground who took material from the Uzbeks, who in turn had used torture to get it from other locals. He thought the material was "worse than dross", yet the UK accepted it.

MI6 didn't have a single operative in the country, he adds. Yet when he met with two separate US ambassadors to Uzbekistan, he says they uttered the phrase "war on terror" as a way of justifying their country's actions. "The British government was, I was astonished to learn, setting out a case to justify receiving torture material, " he says. "I couldn't believe it. There are things you can go along with and things you can't. I really did think we wouldn't stand for that. And I am pretty confident that prior to 9/11 and prior to following the States on this - which is what it's all about - I don't think we would have."

The key phrase was "intelligence sharing", he was told. "But to me it was about the poor bastards I was meeting who'd had their testicles cut off." His job, it was implied, was to show up, shut up, fly the flag, enjoy his whisky at receptions and play golf now and again.

There was another problem too: Nadira Alieva, a young Uzbek woman whom he met in a bar. She was a bright English graduate who, she claims now, didn't know he was an ambassador. "I like older men, " she explains when I ask her what attracted her to Murray.

"I'm not interested in handsome. I think with my brain." As she answers, Murray laughs out loud. It's a bit awkward, but you can understand what she means.

Understandably, rumours about all this started reaching Whitehall, which prefers stable, married ambassadors where possible.

The wheels seemed to be coming off the Murray-Uzbekistan wagon, especially when he moved Alieva into the embassy itself.

Then came accusations of financial impropriety, the weirdest involving the Battlefield Band, a Scottish folk group. It was going to cost [pounds]6,000 to have the band and their PA equipment flown out for a tour of Uzbekistan; instead, says Murray, he bought them gear, thinking other bands could use it on future visits too. This, however, became a sore point with the Foreign Office, which accused him of financial corruption.

Worse was yet to come. "The stuff on human rights, they could live with, " he says, "but when I was going back on the intelligence stuff, saying the intelligence was rubbish and it had been obtained under torture and might be illegal, that was causing problems. But what I didn't know then - and should have - was I was only seeing it in Uzbekistan. If I'd been the ambassador in Saudi Arabia or Egypt or wherever, I'd have been seeing intelligence from their intelligence services relating to the war on terror too. So what I was doing had much wider implications. We now know - but I didn't know at the time - that the Americans had been shipping people around the world to be tortured."

That's a devastating claim, but he goes further. He says it is still happening. "It didn't occur to me at the time, " he says. "In retrospect I think I was on to something much bigger than I knew then. I didn't know how sensitive a point I was pushing.

"That's when the house came down on top of me. I faced the accusations - sex for visas, alcoholism, financial corruption. They said I had one week to resign as ambassador. This was August 28, 2003. They said I mustn't tell anyone about the allegations. If was to resign of my own free will, everything would be okay, and I could continue my career. But if I didn't resign - these are serious allegations.

When I was in London, they advised me not to go back to Tashkent, but said they couldn't stop me. I went back, but when I returned I cracked up. The strain of being there - my wife didn't return - was too much. I actually went nuts."

He was taken back to the UK under medical supervision and put straight into a psychiatric hospital, where he was put on suicide watch.

Back in Tashkent, his staff at the embassy began writing letters of support. They thought their boss was being set up for the drop.

After six weeks he was sent back to Uzbekistan. Then a peculiar thing happened: he developed clots in both lungs. He'd had no warning symptoms, as usually occur; just a sudden pain in his back. He was pumped full of blood-thinners and shipped back to the UK once more. Asked if someone tried to bump him off, he replies simply: "I'm suspicious."

His doctors were suspicious too.He says they told him they'd never seen a case like it.

Craig Murray ended up facing 18 allegations from his bosses, including alcohol abuse (he confesses to liking his wine and whisky, but vehemently denies it impairs his performance), driving a Land Rover down some steps (he says he can't drive) and exchanging visas for sex (he hasn't the foggiest about that one). All but one was later thrown out: he was, however, given an official warning about discussing the allegations with his secretary. It was the most trivial of all the charges he'd faced, and the only one on which he could be tripped up.

Eventually, in London, he was stopped from returning to Uzbekistan when a Foreign Office official told him there was a hiccup in his vetting procedure. He challenged this, but on the same day a London-based newspaper mysteriously ran a report about him. Subsequently he was accused of leaking information to the press and dragged over the coals. "I was angry, and went on the BBC's Today programme, " he says. After that, he was suspended straight away.

A Foreign Office spokesperson told The Herald Magazine that there was little choice in the matter: "In order to perform the full range of duties as required to conduct Her Majesty's government's relations with Uzbekistan, Craig Murray had to enjoy the full cooperation of colleagues and ministers. Given his public differences with the Foreign Office, it was judged this was no longer the case.

"The allegations of misconduct by Mr Murray were made to the Foreign Office and, as a responsible employer, we had to investigate these. Mr Murray was cleared. As for the documents that were leaked to press outlets:

we investigated these but could not conclude the investigation because of Mr Murray's health. Subsequently he applied for early retirement and got it." The spokesperson added: "We take the issue of human rights in Uzbekistan very seriously."

Maybe so. However, a couple of weeks after he received his [pounds]315,000 pay-off from the Foreign Office, Murray is not about to let go of the bone. He's planning to stand as an MP in Blackburn, the constituency of Jack Straw, the foreign secretary. He has no ties to the area, knows no-one there and has no political organisation in place, but says: "I plan to drive up at 3am tomorrow and start searching for a house."

Alieva looks on forlornly. She seems downcast about his plans, expressing doubt about the whole exercise and explaining that she's not "political". She's on a student visa and has to stay in London to study anyway.

Murray, however, is more positive. He plans to marry Alieva once he divorces his estranged wife Fiona. Their relationship, he says, was already on the slippery slope when he met his new girlfriend in that Uzbekistan bar. Fiona has settled in the UK with their two children, Emma, ten, and Jamie, 16; she will, he adds, "quite rightly" receive half his lump-sum payment from the Foreign Office once tax deductions have been calculated.

Murray adds that the journalist Martin Bell, who won an independent parliamentary seat on a sleaze-busting ticket, has offered to help out by speaking on his behalf. "He made sleaze the issue of the 1997 election, " says Murray. "I want to make human rights the issue of the 2005 election. We're getting intelligence through torture on the basis of which the government wants to lock up people here in the UK without a trial. I want to use my standing to hammer that message home."

Still, it is hard to quantify what Murray has achieved so far. However unfounded, the muck thrown at him has left him in a position where he has to explain himself, despite the fact he is probably guilty of nothing more than falling for a younger woman and taking a stand for human rights in a country where the concept is unknown. His chances of winning the Blackburn seat are remote, but in time he might yet go down in history as the first British ambassador to blow the whistle on Whitehall duplicity and simultaneously draw the media spotlight on to a country most people hardly knew existed.

A sudden gust of wind rattles the windows of the flat, and Alieva's crazy phone erupts into life again. Asked if he misses Uzbekistan, Murray thinks for a long time before replying:

"It's on my mind every day." For the first time during the interview he has tears in his eyes.

A small silence descends.

Outside in the communal hallway, people are trudging upstairs noisily. Thumping music begins to flow down from the apartment above. Murray retains a detached reserve and impressive dignity. I ask if he misses the trappings of ambassadorial office. "No. I would only be upset if I didn't have my books, " he says softly.

I believe him.