So in the end, it wasn’t The Donald but Ted Cruz who won. Cruz, the man who claims Obamacare is “the biggest job-killer” in the US, who will “build a wall that works” on the US border, who wants to carpet- bomb Syria until “sand can glow in the dark”, and who has called the Roe vs Wade ruling to legalise abortion a “dark anniversary”.

Perhaps one of Donald Trump’s most unexpected achievements is to make Cruz look mainstream. Cruz comfortably won the first round of the nomination process to be the Republican Party’s candidate for the presidency of the United States, the Iowa caucuses. He’s a sort of hillbilly Nigel Farage from the Right of the Tea Party. Leading the party of Abraham Lincoln. The mind boggles.

I have always thought there is something oddly reassuring about the American presidential primaries. For all that US politics is dominated by money and special interests, the candidates still have to hawk themselves around the cornfields of Iowa and the coffee shops of New Hampshire, meeting individual voters, to stand a chance. Even The Donald had to schlep around the Iowa State Fair — although admittedly he arrived in a helicopter with his name on it.

Cruz’s victory was not the only strange result that the Iowa caucuses threw up. Bernie Sanders, a 74-year-old rabble-rouser from the far Left of the Democratic Party, so much so that he has run against it as an independent candidate in the past, came within inches of beating the favourite, Hillary Clinton.

Something, clearly, is afoot in American politics.

Some people’s reaction on this side of the pond is to watch the US presidential race with amused detachment, safe in the knowledge that such antics could not happen in the UK. I wouldn’t be so sure. British politics have become remarkably volatile and unpredictable in recent years.

A short while ago no one would have predicted that the Scottish Nationalists could turn Scotland into a virtual one-party state, or that the Conservatives would so successfully use money and fear to swing anxious English voters into the blue column. Or that Ukip might top the polls in 2014’s European elections and gain four million votes in the general election.

When Jeremy Corbyn, once a fringe figure on the far Left of the Labour Party, entered its leadership election, his odds of winning were set by one bookmaker at 200-1. Now that he is leader, with a transformed party membership, one of the great parties of British politics looks more like a protest movement than an alternative government.

The politics of identity, of us versus them, is on the rise. “Them” could be bankers, Islam, the establishment, Brussels, the English, the political class, immigrants or any number of other pantomime villains and scapegoats. Whoever your chosen bogeyman, a “straight-talking”, anti-establishment populist is railing against them and gaining traction.

As the political debate becomes increasingly shrill and polarised, what is lost is moderation, compromise and reason.

This febrile and unpredictable mood is on the rise, often in more extreme ways, across Europe too. On the Left, Syriza in Greece and Podemos in Spain have risen to prominence seemingly out of nowhere. On the Right, Marine Le Pen’s quasi-fascist Front National party came second in the French regional elections. The ugly Right-wing Law and Justice Party now runs the Polish government. The neo-Nazi Golden Dawn party now has MPs in Greece.

'The politics of fear and identity, of populists and rabble rousers, is on the rise in Britain and across Europe' Nick Clegg

Whether in the US, Europe or in a milder form here at home, the immediate reason for this tidal wave of populism is the same: people feel economically insecure — their livelihoods damaged, their living standards hit by the crisis of 2008, because of a mixture of greed and incompetence from bankers, regulators and Governments — and political elites appear incapable or unwilling to help.

There are, of course, other reasons too — violent extremism, the collapse in traditional party political allegiances, mass immigration — but the toxic combination of personal economic insecurity and political impotence and incompetence is at the core of so much voter anger and disillusionment across the developed world.

In this climate it is easy for populists who point the finger of blame and offer beguilingly simple solutions to rise to prominence. Without dismissing the political skills of everyone from Ted Cruz to Alex Salmond, from Donald Trump to Nigel Farage, it’s pretty easy to be a politician peddling grievance and division these days. There’s a ready market for the politics of fear.

The much harder task is to stand up for moderation and reason.

Of course, as far as America goes this could all soon feel like much ado about nothing. By Super Tuesday, the biggest day in the US primary calendar, Hillary may have streaked ahead of Sanders and a more mainstream Republican, such as Marco Rubio, may have broken the Trump-Cruz duopoly. After all, idiosyncratic Iowa Republicans chose the Cruz-lite Rick Santorum last time around, and that proved to be the high point of his campaign.

But even if that happens we should not just chalk it up as some quirky American flash in the pan that has no relevance to our lives. We are not somehow immune. The politics of fear and identity, of populists and rabble rousers, is on the rise in Britain and across Europe.

Liberals, moderates and anyone who believes in reason and evidence cannot afford to shrug their shoulders and just hope it goes away. Moderation is a precious thing — and it needs to be fought for.