With Boris Johnson's expected coronation as Prime Minister on Tuesday Britain joins the growing ranks of developed countries governed by populist politicians. Whatever Theresa May was, she was not a populist and nor were her predecessors. But Boris Johnson, with his charismatic, anti-establishment and nationalist politics is right up there with Donald Trump.

And yes, I know: the idea of this Eton-educated scion of the British upper classes being “anti-establishment” seems nonsensical. But populism has nothing to do with the social origins of its leaders. Nigel Farage used to be an investment banker. Donald Trump is a billionaire. It is about the people they seek to represent – often dismissively labelled the “left behinds”, often non-graduates in low-paying jobs in non-metropolitan areas. The force that gave us Brexit.

By its very nature, populism is not a coherent political philosophy. It is more visceral – the inarticulate fury of people who feel they the plaything of remote forces beyond their control. Its origins lay in the disruption that followed the 2008 financial crisis, in which bankers were bailed out but not the people. They suffered insecurity, economic uncertainty and the longest pay freeze since the Napoleonic Wars.

Populists linked arms with the more traditional, reactionary nationalist politicians against the globalist, liberal-democratic “establishment”, that has dominated the media and politics for the last three decades. Think of Brown, Clegg and Cameron standing in line in the 2010 election: three identikit, pro-European, neoliberal suits. Think of the leaders of the European Union. That is the establishment against which populists believe they are revolting.

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In France, the Gilet Jaunes protest continues, after nine months of street demonstrations, violent confrontations and petition-signing. It is inchoate, unpredictable and largely leaderless. But as anyone visiting France this summer will testify – it is everywhere. And it is overwhelmingly white. The repressive measures used against them by President Macron would be a national scandal were they used here.

As Donald Trump demonstrated last week, populism has a strong racialist strand, though it is not simply a fascist movement as many on the left claim. Donald Trump is not an ideological white supremacist (though perhaps in his case that should be “orange supremacist”). He is above all an opportunist, ready to use whatever comes to hand to promote his personal popularity. With him, ratings mean more than political conviction.

But that doesn't mean he can plead innocence after his genuinely shocking attacks on the democratic “women of colour” last week . This began as crude electoral politics. He was trolling the Democrat Party, and the media, by singling out the radical “squad” of Democrat congresswomen, as they're known. He wants the Democrats to be indelibly associated in the public mind with its multicultural Left, the better to win over white middle Americans and moderate Latinos. But he unleashed something deeply worrying.

As the chants of “send them home” erupted at his rally Trump's trademark smirk seemed at first to nodding along. But even he now seems uneasy about the genie he has uncorked. Not since the 1960s has racism been a factor in US presidential politics – at least not overtly. Barak Obama avoided playing the race card. Trump has now placed it firmly on the table, and it isn't going to go away.

Donald Trump's flirtation with racism could actually lose him the next election, because many middle Americans are appalled at his behaviour. The United States prides itself, after all, on being the most multi-cultural, multi-racial society in the world – one which used to welcome “the huddled masses” of immigrants with open arms.

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But liberals shouldn't get their hopes up. There is no rule that says racism can't help win elections. These are troubled times, and politicians need to exercise responsibility so as not to conjure forces they cannot control.

Boris Johnson is also often called a racist, and a homophobe. This is largely because of his describing burqa-wearing Muslims as “bank-robbers” and “letter boxes”. The future PM is not himself racist, as anyone who knows him can testify, but that doesn't mean he is immune to its compelling force.

As London Mayor, Boris Johnson made great efforts to win the support of Muslims in that multi-racial city. He included many non-whites in his cabinet. When he takes over this week we can expect him to make great play of his progressive liberal credentials. He will remind voters that the infamous Telegraph article argued against banning the burqa.

However, there is no doubt that his signature politics of Brexit, while not racist in itself, arises at least in part from resentment at immigration. Many of Johnson's supporters are the kind of people you might find at Donald Trump rallies. His first test as Prime Minister should be to create clear multicultural water between himself and the American President – his equivocation last week about labelling Trump's remarks “racist” does not augur well.

Johnson desperately needs the White House to deliver some kind of free trade deal that will show Europe that Brexit Britain means business. His first foreign visit as Prime Minister will be to the Trump Residence to plead his case for special treatment on trade. If Mr Johnson has any integrity, he will also make clear his concern at Trump's racist rhetoric – but I wouldn't hold my breath.

It's an open secret that Johnson is looking to an early election to capitalise on Labour's internal problems, which are to do with allegations of another kind of racialism: anti-Semitism. However, Westminster is now a four party political system with Nigel Farage's Brexit Party and the revived Liberal Democrats challenging hard. Boris Johnson may have to seek the support of the Faragiste MPs to form a government. That could shift British politics further to the populist right.

Nigel Farage's party is not an overtly racist party either, though his former vehicle, Ukip, has recently been showing clear signs of becoming one. But there is no doubt that Brexit Party supporters are hostile to immigration. Racism exists as a latent force in all parties, but in nationalist ones in particular. Our own Scottish National Party used to have in its ranks “anglophobes” like the poet Hugh MacDiarmid, and “blood and soil” factions like “Seed of the Gael”.

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However, the SNP also stands as a beacon of hope in this darkening night of populism. For the party expunged all trace of anti-English racism from its ranks in the 1960s and 70s. It is now arguably the most progressive, anti-racialist political party in the UK. Of course, there are still some SNP supporters around who hate English people, but they are not tolerated.

There is a huge temptation for SNP politicians to subtly exploit latent anglophobia when arguing against “Westminster rule”. But the SNP has shown that it is possible to conduct nationalist politics with great success by avoiding these “tropes” as they're called. Indeed, the SNP's electoral success has largely been built on the claim that Scotland could be more progressive and more multicultural than the UK. It has raised diversity and antiracism to the level of a national political programme. In these difficult times, we should be thankful for that at least.