We were all too busy chattering about how David Cameron's mishaps over pasties and jerry cans were benefiting Ed Miliband to see it coming.

In Bradford West, one of Labour's safest seats, Galloway stormed to victory with a 10,000 majority on a 36% swing.

He won more votes than all the other parties combined. If none of us politics nerds had noticed what was happening in Bradford, nor had the Labour leadership. Yet in the Tories' worst week since they came to office, Galloway has handed Labour its worst by-election defeat and left the Labour leader humiliated. If he can't win here, now, where can Ed Miliband win?

I've been a Galloway-watcher for three decades since I first met him during the workers' occupation of the Plessey electronics plant at Bathgate in 1982. I was doing a BBC documentary on the strike. He was a sharp-suited Scottish Labour Party chairman, the youngest in history, who charmed the pants off the mainly female workforce. Galloway was tipped as a future Labour Scottish Secretary. But he was always too hot for the Labour establishment to handle, and controversy followed him like a black dog. Whether it was the Dundee Labour Club accounts in the 1970s, or his expenses when he was with the charity War On Want in the 1980s, or donations to his Mariam appeal for Iraqi sanctions victims in the 1990s, George Galloway has spent far too much of his time fending off allegations of financial impropriety. But it has left him a wealthy man.

The Daily Telegraph accused him of taking money from Saddam Hussein in 2004; Galloway ended up taking money – £150,000 – from the Daily Telegraph for defamation. There's scarcely a news organisation in Fleet Street that hasn't paid George Galloway large sums in damages, most recently against News International for tapping his phone. His finest hour, before Friday morning, was in 2005 when he faced down a US congressional committee in Washington that had accused him of diverting oil money from Saddam Hussein. His worst was probably on the floor of the Celebrity Big Brother house in 2006 when offering to be Rula Lenska's pussy cat. Labour – who had expelled him in 2003 over Iraq – thought that this creepy appearance had destroyed Galloway forever. How wrong they were.

So is Bradford West a one-off? Labour predictably insist that the result is a mid-term protest vote and the constituency will return to the fold at the next General Election. I wouldn't be so sure.

There is certainly only one George Galloway. Having stood against the Respect MP in the 2009 election for rector of Edinburgh University, I know how good he is. I won, as it happened, but Galloway was by far the more able campaigner.

His victory in the Bradford West by-election, the most sensational by-election victory in modern history, is emphatic confirmation of his extraordinary political gifts. He is the most charismatic public speaker of his generation, a conviction politician of the old school, who connects with voters across party and racial lines. A populist, a self-publicist, and an opportunist – what politician isn't – Galloway has been written off many times, but he always seems to come back stronger. This is more than a fluke, and Galloway is a tenacious fighter who will work hard to consolidate his hold on this seat. He will be a high-profile figure in the House of Commons where his debating skills will be put to good use condemning the war in Afghanistan, denouncing bankers and plutocrats and accusing the Coalition of abandoning the victims of Britain's longest economic downturn since the 1930s. He will give voice to extra parliamentary movements like Occupy, to the young unemployed, to impoverished graduates, and above all to the Asian voters.

The Respect MP is often accused of tailoring his message and even his lifestyle to the Muslim vote – 38% in Bradford West. But if so, he has been doing it for nearly 40 years. In the early 1970s, Galloway took up the then rather unpopular cause of the Palestinians in Israel and was instrumental in twinning Dundee With Nablus on the West Bank in 1980. That began a lifelong association with Muslim politics in the Middle East. Galloway is actually rather a quiet man in private: he doesn't drink, and often seems a little distracted. His energy is kept for the platform, which he commands like an Old Testament prophet. All of which commends him to British Muslims.

But there is more to this than the politics of identity. Galloway has tapped into a widespread sense of alienation following the financial crash. Just as conventional politics is breaking down in Greece, Spain and Portugal under the strain of austerity, so communities like Bradford are abandoning the establishment parties and turning to populists. This looks like the politics of despair, the politics of depression.

And as George would put it: cometh the man, cometh the hour.