'Please,' a member of George Galloway's staff asks me, before I meet the newly elected Respect MP for Bradford West, "don't turn this into a lazy rehash of the same old stuff."

"You don't know what you're asking there," I tell him. "The lazy rehash has served me effectively for years. I've made that modus operandi my own. Why go changing now?"

The trouble with this sort of request – entirely understandable in Galloway's case – is that those words stay with you for days before a meeting. Every unwelcome image, true or invented, from your subject's life starts flashing in your brain like neon. What "same old stuff" did he mean? Galloway's brief incarnation as a feline impersonator, dressed in a leotard, lapping milk from the hands of Rula Lenska, on Celebrity Big Brother in 2006? Or the kind of story that creates visions of George Galloway drinking Cristal champagne from the bottle, in the Jacuzzi at one of his three-dozen mansions on the Cap d'Antibes, properties purchased with money that should have gone to the world's starving? (Such is the hallucinatory, and libellous, tone of certain articles in the press-cuttings file dedicated to the politician, a lifelong teetotaller.) Galloway pestering Saddam Hussein for cash advances? (Another defamatory accusation that cost several newspapers a total sum in excess of £2m.)

We meet in the outdoor café by his office at Westminster, a location that allows the 57-year-old to ignite his trademark cigar. He is softly spoken, modest in manner, and cautiously welcoming.

The difficulty for George Galloway's enemies is that, while allegations about serious misconduct have been many and various, every time they have been tested in court it's the man from Dundee who has carried the day. I tell him how, the previous evening, I was speaking to another icon of the Left (a writer, not a politician) and told him that, for all my best efforts, I couldn't see what it was about the MP that engendered such intense hatred.

"And what he said," I tell Galloway, "was this: 'How about the overweening conceit?'"

"You'll have to make your mind up about that."

"Where do you think he got that idea?"

"I don't know. He certainly cannot know me. I am not arrogant. If I were ruthlessly ambitious I would have pursued a different course, like all the other Reds who joined Labour around the same time as me. Alistair Darling, for instance. John Reid. I would have tiptoed around like they did, according to the prevailing wind. I did not."

Galloway's Respect Party campaigned in Bradford West on a platform that embraces Socialist reform, abolition of tuition fees and withdrawal from foreign military adventures. (The name is an acronym: Respect, Equality, Socialism, Peace, Environmentalism, Community and Trade unionism.) He won a sensational victory in the West Yorkshire constituency, at initial odds of 33-1.

"Did you hesitate," I ask Galloway, "before agreeing to this interview?"

"I hesitated a great deal. I agreed only because it was The Independent on Sunday. I'd decided after my last newspaper interview: fuck this for a game of soldiers. But I will deal as honestly as I can with anything that you have to ask."

You can't blame him for a degree of circumspection. As my Independent colleague Patrick Cockburn wrote, in the aftermath of the Bradford by-election: "The ferocity of the attacks on George Galloway by the British commentariat is one of the most revealing outcomes of his victory. Interviews with the MP were largely a shower of insulting and unproven allegations. [His questioners] were convulsed with rage because Mr Galloway had said complimentary things to Saddam Hussein and Bashar al-Assad when he met them. Of course he had, as had every other visitor, from Donald Rumsfeld to Tony Blair." It was not impossible, Cockburn conceded, that there existed some legitimate case against George Galloway, "but if so, it was never made".

The orthodox form of an interview, I remind Galloway, was defined by Jessica Mitford in her Poison Penmanship: The Gentle Art of Muckraking, and goes like this: the questioner cajoles the subject for an hour or so, reserving any compromising inquiries for the second half. In his case, at this time, I suggest, such a strategy would be impossibly duplicitous: "Because everyone with any interest in you will have read that recent piece in the New Statesman, by Jemima Khan, which began with the line: 'George Galloway is a Muslim.'"

The New Statesman article makes the assertion, relying on testimony from an un-named friend of its author, that Galloway was inducted into the Islamic faith at a hotel in Kilburn, north London.

"Can we first address the basic suggestion that you are a Muslim: is that true?"

"The fact that there is such an infatuation with this," he replies, "speaks volumes concerning the attitudes to Muslims in this country. The proper way of framing that [question] would be as an accusation."

"I don't consider it to be an accusation."

"I accept that it isn't, from you. Other newspapers have voiced it as an accusation. Nobody would pursue an MP asking them if they were, er..."

"Parsee?"

"Yes. Or ask, 'Are you a Jew?' I have my answer and I won't move from it. I believe in God." (Galloway was raised a Catholic.) "I have always believed in God. I don't go into details of my faith beyond that. What I will tell you is that the New Statesman story is complete garbage."

"Planning to sue?"

"Well, the statement, 'George Galloway is a Muslim' is not defamatory, that's the problem. Jemima Khan said she knew somebody who witnessed some voodoo ceremony – my words, not hers – in Kilburn." Galloway says that he denied this suggestion and added, "'Nobody you know was ever at such a ceremony because it never took place. So whoever told you that is lying to you.' That exchange does not appear in their story because it would have invalidated their opening line."

(Jemima Khan, who emphatically rebuts Galloway's claim of a denial, told me that he simply said: "Have we finished here?")

"Of course, were you to attempt to sue on the simple basis that somebody had inaccurately described you as a Muslim, that would place you in a rather awkward position."

"Exactly. It's as if you said to me: 'You are a homosexual...'"

"That was my next question, as it happens, you big Scots poove."

Galloway has the grace to laugh.

"...because I do not regard being a homosexual as shameful. The idea that I converted to Islam in a ceremony in Kilburn, or Karachi, or Kathmandu... anywhere... is rubbish. I told Jemima Khan so at the time, though [my assertion] was not reported."

"And yet the idea that you might be a Muslim is something you won't comment on?"

"That is as far as I go on it."

"It matters though, doesn't it? Because throughout your career, there's been a consistent overlap between your political beliefs and religious principle."

"Yes. But if I get into which branch of belief I'm in, there are too many downsides."

The downsides to being a Roman Catholic with empathy for Islamic peoples would appear to be negligible. Having spoken at some length to Yusuf Islam, formerly Cat Stevens, and observed the way that his public conversion to Islam precipitated a deluge of questions designed to entrap him – questions concerning the actions, however appalling, of anyone claiming, however tenuously, a connection with the Islamic faith – I tell Galloway I think I can take a guess at his motives for ambivalence here. No comment. He knows Yusuf Islam well, is all he will say.

You may recall Tony Blair's recent appearance before the Leveson Inquiry, when he argued that, once you have a British media group on your case, the consequences are "relentless and unremitting". Blair, I imagine Galloway thinking, doesn't know the half of it.

If the only thing George Galloway had ever achieved, in his whole life, was his coruscating demolition of Senator Norm Coleman, in the wake of unfounded accusations that the Scotsman had been a beneficiary of Saddam Hussein's oil revenue, his name would never be forgotten.

Galloway delivered his speech to the US Senate in May 2005, after being falsely accused of taking bribes from Saddam Hussein (under cover, it was alleged, of the Mariam Appeal, the leukaemia charity he'd founded, named after a young girl he rescued from Iraq). His rebuttal remains one of the bravura performances of modern international politics. Senator Coleman, a Minnesota Republican described by Galloway as "a pro-war, neo-con hawk and lickspittle of George W Bush", had made the unfortunate error of underestimating the man described by arch-Conservative commentator Frank Johnson as one of the greatest orators of his age.

"Senator," Galloway announced, before the Upper House in Washington. "I gave my life's blood to try to prevent the mass killing of Iraqis by the sanctions against Iraq. Which killed a million Iraqis, most of them children. Most died before they even knew that they were Iraqis. I gave my heart and soul," he continued, "to stop you committing the disaster that you did commit in invading Iraq. I told the world that your case for the war was a pack of lies. I told the world that Iraq – contrary to your claims – did not have weapons of mass destruction. I told the world – contrary to your claims – that Iraq had no connection to the atrocity on 9/11/2001. I told the world – contrary to your claims – that the fall of Baghdad would not be the beginning of the end, but merely the end of the beginning. Senator, in everything I said about Iraq, I turned out to be right, and you turned out to be wrong. One hundred thousand people have paid with their lives. Sixteen hundred of them [were] American soldiers, sent to their deaths on a pack of lies. Fifteen thousand soldiers wounded; many disabled for ever; on a pack of lies."

Reviewing his testimony, which is posted on YouTube, and is delivered with the kind of fearless expression that Sir Alex Ferguson, speaking in a different context, once described as "the glazed eye", you can't help thinking what a defence counsel he might have made. The broadcaster Anne Robinson observed that Galloway had "put the pride back into British politics".

"George Galloway's focus on 13 years of sanctions against Iraq is portrayed as outré," observed Patrick Cockburn. "But I was in Iraq for many of those years and I watched the collapse of a whole society into poverty. I remember being mobbed by farmers showing X-rays of their sick children, hoping I might be a doctor. Hundreds of thousands died unnecessarily. Galloway was one of the few politicians who tried to make an issue of this man-made catastrophe. Unfortunately, he failed."

The widespread loathing he engenders, especially in the UK, Galloway believes, is born of an acknowledgment that "I was right on the big issues. The first time The Sun put me on the front page, under a screaming headline containing the word 'traitor', was 20 years ago. I'd appeared at an event with Gerry Adams and Martin McGuinness. I argued that you cannot bring people into the political process without talking to their leaders."

"Even though you'd have been aware that McGuinness, say, was – just possibly – a very senior figure in the IRA?"

"Yes."

"What you're saying is that sometimes, in politics as in journalism, you have to deal with people that you would not, to use an ungrammatical sentence, wish to breathe the same air as?"

"Exactly. Consider the names of the terrorist leaders who ended up dining with the Queen at Buckingham Palace. From Kenyatta and Makarios through to Bashar al-Assad, who slept as a guest there in 2005. The Sun called me a traitor back then, even though, it later transpired, Mrs Thatcher and John Major were already in negotiations with those men. I was right about that. I was right about Palestine," says Galloway, a fervent opponent of Zionist expansionism, "from the start. I was right about Iraq."

"That could sound very like arrogance, especially since you have operated largely on the periphery of British politics. It's all very well declaiming over a cigar when you're head of state. Even then, there's a fine line between self-confidence and arrogance."

"My belief that I was right on these questions is not arrogance. It is a statement that invites my adversary to say: 'He was right and I was wrong, back then. Perhaps I am wrong now.' I don't see where arrogance comes in to it."

The unease surrounding George Galloway's interaction with Saddam Hussein centres around his greeting to the Iraqi leader in 1994 ("Sir, I salute your courage, your strength and your indefatigability"). Galloway has always insisted that this compliment, which was translated for him, referred to the Iraqi nation, not the dictator. k

("I understand Arabic," says Anas Altikriti, a leading figure in the anti-war movement. "His statement was taken completely out of context. When he said 'you', he meant the people. Even the interpreter got it right.")

"And yet," Galloway recalls, "when I presented, in the US Senate, my denunciation, in Hansard, of Saddam Hussein, two years previously, as a bestial dictator, people ignored that as if it never existed."

"Just staying with Iraq and the question of weapons of mass destruction," I say, "an eminent professor of my acquaintance keeps, in his office, a poster calling for a full inquiry into the death of Dr David Kelly."

"I am part of that campaign."

"You believe Kelly was killed?"

"Yes."

"By MI5?"

"I don't know by whom. To me, his death was like that bad joke about the black guy in the river in Alabama with bullet holes in his back, and the coroner declaring it 'The worst case of suicide I have ever seen.'"

I mention Jacques Vergès, the maverick French lawyer who – though his flexible moral spine makes him the antithesis of Galloway in many ways – has tormented the French establishment for years concerning its treatment of Islamic states. "Vergès has spoken about fears for his safety. Do you have any worries in that regard? I know you recently spoke about an unexplained break-in where your possessions were disturbed..."

"That one actually goes back three years," Galloway says. "But we had a life-threatening situation only three days ago. Two men smashed in the door of my house at 6.15 in the morning. They came in, presumably to begin searching. My secretary was sleeping on the top floor. My wife and I were on the second floor, behind a locked door. They went into [the secretary's] bedroom, then left: either because they realised it wasn't me in the room, or simply because it was occupied. They walked out casually, down the stairs."

"Any arrests?"

"No."

"Fingerprints?"

"No. They may have been ordinary burglars. But there are alarms, and clear signs that the property has CCTV. This happened in broad daylight."

"Other politicians are usually described as 'meeting' world leaders. You are generally reported to be 'hob-nobbing' or 'cavorting' with them. Fidel Castro, for instance.

"Well, Castro is another kettle of fish. I admire – love – Fidel Castro. I love the Cuban revolution. That doesn't mean I think everything there is rosy. But I believe Castro is one of the greatest men of the 20th century."

"When you first led an aid convoy to Gaza, in 2009, you said, 'If I told the boys,"Break out the Kalashnikovs now," they'd do it.' Those aren't the words of a pacifist, are they?"

"I am not a pacifist. I am a revolutionary. I am a Socialist who doesn't like Capitalism and who likes Imperialism less. I am a revolutionary and I support the armed struggle where there is no alternative."

"In the UK?"

"It is not applicable here. And what I don't support is terrorism; individual acts of atrocity, for theatre. Terrorism is never justified."

When he goes to Bradford West now, armed with this kind of rhetoric, a friend tells me, George Galloway is mobbed "like a rock star".

Anyone acquainted with Bradford will know that, in this increasingly homogenised nation, it's one of those cities – Liverpool is another – which gives you an immediate sense of entering a uniquely distinctive world. Whereas most football clubs' mascots strive to radiate exoticism by dressing as jungle beasts, Bradford City's vision of an alien figurehead ("The City Gent") wears the classic apparel of a London banker.

"Bradford is unique, and has a boundless potential which I believe is symbolised by the football club. [Demographically] it is the youngest city in England. By 2020 it will be the youngest in Europe, with half the population under 25. Which ought to be a blessing, but could be a time bomb. Because so many of them, if things don't change, will be unemployed."

In Bradford West, as has sometimes been overlooked, Galloway won well in non-Muslim, as well as majority-Muslim, wards. Polls indicate that Respect was especially successful in recruiting Liberal Democrat voters, many of whom had initially defected from Labour over tuition fees and war.

I sometimes wonder, I tell Galloway, if the Liberals remember who used to support them. "If they don't remember now," he says, "they will in November, after the by-election in Manchester Central. Which we are fighting to win. The students, who voted Liberal by the hundreds of thousand, will turn against them. In Bradford I won 83 per cent in the university ward. Because I was the only candidate who opposed tuition fees when they were introduced, and continue to do so. The Liberal Democrats have made a grotesque error of epic historical proportions. And I believe they are coming to realise that."

George Galloway was born in Dundee on 16 August 1954. The unauthorised biography Gorgeous George, by David Morley, a copy of which, I tell him, is concealed in my bag (Galloway groans), implies, among other things, that he was brash and assertive at school. Enemies claim that his own memory of an impoverished childhood exists only in his head. His father, they insist, was a well-heeled engineer, who went on to become a teacher.

"He was a shop-floor worker who left school at 14," says Galloway, who has an older sister and a younger brother. "He became a teacher in his fifties because he went to night school and gained qualifications. I was born in a slum," he continues. "When I was five, we moved to a council house and I lived there till I left the family home. There was one wage. My father was a Socialist. I never left the parameters that he taught me."

"You don't drink alcohol; with no disrespect to Scotland or your generation, that's unusual for a man of your age and background."

"It is. I have never tasted alcohol. My father believed drink was a real evil; that working men, and the revolution, were held back because of it."

"Some crass part of me is having visions of you sitting cross-legged in a poncho listening to your prized Bob Dylan albums, smoking cannabis."

"I have never even seen cannabis, or any other drug. I am as militant against drugs as I am against drink."

"Gorgeous George alleges that you once pulled a teacher into a swimming pool..."

"A complete lie. That book is filled with that sort of stuff."

A member of the executive of the Labour Party's youth wing at 16, he was secretary organiser of the Dundee Labour Party at 26. After a trip to Beirut in 1977, he became a passionate supporter of the Palestinian cause. (In the course of our conversation, Galloway floats the argument that it would be preferable if Iran acquired nuclear weapons, because that might temper and rationalise any Israeli impulse to bomb Tehran.) Dundee City Council, in his time there, flew the Palestinian flag. The city was twinned with Nablus, on the West Bank.

In November 1983, Galloway came to London as director of the charity War on Want. Under his dynamic if uncompromising leadership, membership increased from 4,000 to 50,000. The budget rose from £1m to £10m. His office was burgled three times in this period. k

"It has been suggested that you took money, at War on Want; funds that came from charitable donations. There was no allegation of criminality, but if I remember correctly, you paid some back?"

"£1,800. Taxi fares. I was fully cleared by the auditor's inquiry," Galloway says. "That doesn't stop it being endlessly rehashed."

He met his first wife, Elaine Fyffe, when he was 15. They married when he was 28. It's difficult to broach certain aspects of Galloway's history without addressing allegations from what we find ourselves referring to as "the Charge Sheet". For a man of moral principle, he has suffered multiple reverses in the battle for monogamy. Having partied with women on the Greek Island of Mykonos in 1985, he separated from Elaine two years later. In 2000, he was married again, to Amineh Abu-Zayyad, a biologist, in a Muslim ceremony. By 2009, he was married to his Lebanese former researcher Rima Husseini. The complexities of some alliances would not be out of place in one of Congreve's more intricate farces, and the usual requirement for a Muslim bridegroom to convert has meant his marital history has come under new scrutiny. His current wife, Putri Gayatri Pertiwi, is a Dutch-born academic of Indonesian origin, 30 years his junior. They met in Amsterdam and married earlier this year.

"I have been lucky enough to know intelligent and beautiful women," Galloway says, "one of whom I am married to. I prefer the company of women. I marry the women I am with. I can see that looks bad on the Charge Sheet. But this marriage is my last."

The turbulent and eventful nature of his matrimonial history in some ways mirrors his relationship with mainstream politics. He won Glasgow Hillhead for Labour, ousting Social Democrat Roy Jenkins in 1987. In 1997 and 2001, he won Glasgow Kelvin for Blair's party. He was expelled by Labour in October 2003, following robust declarations concerning "Tony Blair's lie machine". In May 2005, he won Bethnal Green for Respect; the sitting Labour MP, Oona King, had supported the Iraq War.

Just as the victories in Bethnal Green and Bradford West seemed to devolve from his own character, so the abuse he has attracted has been highly personal. "I remember what Christopher Hitchens said about you." ("He looks like what he is," said Hitchens, a privately educated advocate of intervention in Iraq. "A thug... a working-class wide-boy... a cheap character and a short-arse.")

"What Hitchens said," Galloway replies, "referred essentially to my class. He meant I was some scruff from the streets..."

"Who should know his place. Condensed into three words, what he's saying there is: 'Vulgar little man'."

"I am not vulgar, as it happens. I know what many of that class of person think of me. It hurts. And it unnerves me a little."

"You recently admitted to feelings of insecurity, if not diffidence; that might surprise people."

"I do have insecurities and they are obvious to those who know me well. I am one of 5 per cent of members in this building who never went to university. I pinch myself when I find myself in certain situations. How could someone who grew up where I did get here? I do feel uncomfortable in the presence of certain people. The gregariousness I display is an act."

"An act? Quite a good one."

"It is an act."

"Watching you speak in public, you seem to have overcome your self-doubt quite effectively."

"I am at my best when I'm performing. On a platform, with a big audience, I come alive. I know I am good at that. When I'm doing that I feel I am flying. But my first words, afterwards, are always: 'How was that?' I ask myself that question again, later. And again, even later, as I lay awake in bed."

"So – given those acute instincts and fears – what persuaded you to go on Celebrity Big Brother where, if you'll pardon my French, I thought you made a total fucking dick of yourself."

"I have friends who agree with you. But I have heard it said that I won in Bradford because so many young people saw me on Big Brother."

"I see. People who thought: 'Ah. At last. A Scotsman who dresses as a cat and simulates licking milk from the fingers of a Buddhist actress: that's who we want as our democratic representative?'"

"If I'd been a bad cat everybody would have forgotten it by now. The regrets I have about being on Big Brother are that I ended up as mad as everybody else. It did raise money for Palestinian refugees, and it also made me money, which I spent on staff." (And, friends say, on an expensive divorce.)

When I ask George Galloway the question, "Where is the Left?" in the face of an imploding European economy so subservient to the market that even Conservative newspapers have been asking if we still inhabit a democracy, he replies: "We are here. We are back. I think there is a total, as George Bush would put it, misunderestimation of the nature of this crisis. I think those in power assume the current paradigm will last for ever. I believe they are mistaken. That's why I describe myself as a revolutionary. In Holland, a group called the Socialist Party is leading in the polls. They may win. They are former Maoists, for God's sake. Think about the Bradford Spring. The defeat of Sarkozy. Think about Greece, and Spain. Revolution suddenly doesn't seem quite such an outlandish idea any more, does it?"

From Galloway's point of view, as the current political crisis threatens to enhance the fortunes of all kinds of smaller, unorthodox parties, the great question for Respect is this: can one remarkable, albeit controversial, leader disseminate his charisma throughout the organisation?

For the Right, he remains half-demon, half-figure of fun. Immediately after I left Galloway, I stopped in a café round the corner and put in calls to senior figures on publications not naturally favourable to him.

"Answer me this," one said: "Do you think Galloway could have won in Bolton without pandering to the Muslims?"

"Bolton?" "Sorry... Blackburn."

"Do you think," I asked him, "that your MP in Broadstairs, or Basingstoke, or Beckenham or wherever it is that you live, could have won without pandering to the golf crowd?"

An amiable laugh. "He'll go away eventually," the reply came. "Like any other pantomime villain."

How many times has Galloway's unsettling vision been written off? In 1984, he had "mellowed into a moderate" (The Sunday Times). In 1987, he was "just another fallen left winger" (The Daily Mail). In 2005, "Galloway will fade away. He should make the most of his moment of glory" (The Times).