There was a telling moment at the end of Thursday night’s ludicrous non-debate.

Four of the five speakers – Ed Miliband, Nicola Sturgeon, Plaid Cymru’s Leanne Wood and the Greens’ Natalie Bennett – moved into a little huddle of smirking self-congratulation. Meanwhile, on the right, Nigel Farage stood alone, exiled to the edge of the stage.

What that image symbolised is perhaps the most powerful and the most dangerous force in British politics today – a new brand of Left-wing populism that peddles a message of class resentment, seeks to profit from a rhetoric of division, and holds up a fantastic, fairytale vision in which, if only the rich are properly squeezed, the government can splash money around to its heart’s content.

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Isolated: Four of the five speakers moved into a little huddle of smirking self-congratulation, while on the right, Nigel Farage stood alone

Nicola Sturgeon, Plaid Cymru’s Leanne Wood and the Greens’ Natalie Bennett hug as Ed Miliband looks on

As the editor of the Spectator magazine, Fraser Nelson, noted in an astute essay this week, this phenomenon is not limited to Britain. Across the Western world, it taps into ordinary people’s fears that ever since the financial crash of 2007-8, the system has been rigged against them – the same fears that helped to drive the rise of Ukip.

And not surprisingly, it has proved most seductive in countries where the impact of the recession was far greater, notably the bleeding economies of the Eurozone.

Already this strange blend of 1960s-style student-union idealism and old-fashioned hard-Left class warfare has catapulted the anti-austerity Syriza to power in Greece. Indeed, only this week there were renewed warnings that Greece’s new hard-Left rulers might pull out of the euro and default on their debts, with devastating repercussions for the European economy.

Elsewhere, similar gaggles of socialist professors, student activists, high-minded liberals and unrepentant class warriors are carrying all before them. The most extraordinary example is the Spanish party Podemos, which was founded last year by a 36-year-old political science lecturer called Pablo Iglesias.

With the exception of Mr Farage (pictured), the speakers were united in their preposterous belief that there is an easy, painless answer to deficit reduction

Today, Podemos is the most dynamic force in Spanish, if not European, politics, with 350,000 members and five MEPs. Like its Greek counterpart, it promises jam for everyone, except the rich. Its programme is full of woolly, well-meaning waffle about liberty, equality and fraternity, but the specifics are simply old-fashioned tax and spend, cranked up to the maximum.

As the New York Times remarked, Podemos’s manifesto ‘reads like a wish-list, with little detail about how it could be financed at a time when Spain is still struggling under a heavy debt burden.’

But in a political landscape where so many are bruised by austerity, this kind of fairytale economics, in which debts can be wished away with a magic wand, has a terrifyingly potent appeal.

It is this lazy, demagogic populism – blame the bankers, soak the rich, promise billions for all and pay homage at the shrine of the NHS – that has defined Ed Miliband’s leadership of the Labour Party.

Indeed, it is this populism that unites him with his rivals in the SNP, Plaid Cymru and the Green Party, who appear to believe that Britain’s national debt will simply disappear if they close their eyes and make a wish.

I doubt I am alone in finding this election campaign one of the most disheartening in living memory. All the parties are locked in a demeaning bidding war, promising endless impossible goodies in return for our votes.

Thursday’s leaders’ debate, though, really took the biscuit. With the exception of Mr Farage – himself a populist, though of a different stripe – the speakers were united in their preposterous belief that there is an easy, painless answer to deficit reduction.

The fact that parties such as the Greens and the SNP believe this kind of twaddle does not surprise me at all. The depressing thing, though, is that Mr Miliband earnestly believes it, too.

Ever since becoming Labour leader in 2010, this quintessential Hampstead intellectual has been convinced that Britain is on the brink of a dramatic conversion to the politics of the Left. He is the first Labour leader for almost two decades who instinctively dislikes capitalism, distrusts the free market, sneers at businessmen and despises talk of wealth creation.

What Mr Miliband peddles is a simplistic credo of heroes and villains – for example, saintly NHS nurses on the one hand, villainous City financiers on the other.

Gone is the mantra of ‘One Nation Labour’. Instead, the Labour programme offers only what critics describe as ‘the politics of division’.

In different circumstances, this formula would take Mr Miliband only to an ignominious and well-deserved defeat. But these are strange times. As we saw in Thursday’s BBC TV debate, in which Mr Farage loudly complained about the apparent Left-wing bias of the audience, there is a distressingly large and vociferous market for Mr Miliband’s class-war politics.

Labour's Ed Miliband, SNP's Nicola Sturgeon, Ukip's Nigel Farage, Green's Natalie Bennett and Plaid Cymru's Leanne Wood took part in the debate on Thursday

For five years, the Coalition has struggled to find an answer to the anxieties that haunt so many families: stagnant pay, rising inequality, overcrowded schools and hospitals, creaking infrastructure. And as a result, propped up by his fellow demagogues in the SNP, Plaid Cymru and the Green Party, the Labour leader may soon be walking into Downing Street.

The dangers of this kind of Left-wing populism are very clear.

Across the Channel, French president Francois Hollande came to power with a similar student-union-style programme of higher taxes, increased spending and no austerity. As in Greece, the result has been disaster, with French businessmen fleeing abroad, unemployment at more than ten per cent and the economy in permanent stagnation.