Conservatives once boasted that they were the grown-ups, even if they did say so themselves. They conserved the best of the past and believed in the sensible management of the world as it is, rather than in dangerous fantasies about the world as it might be. Hold out as their opponents might, eventually they would understand that conservatism was just common sense.

“Once again, the facts of life have turned out to be Tory,” declared Margaret Thatcher in 1976, as she prepared for one of the long periods of Conservative rule that have dominated British history since the 1880s. Dozens of respectable figures have agreed and played with variations on the theme of: “If you are not a socialist at 20, you have no heart. If you are still a socialist at 40, you have no head.” Conservatives have condescended to allow that sensible people might have wild ideas about subjects they know nothing about. But as Robert Conquest, the great historian of the crimes of communism, said in the first of his three laws of politics: “Everyone is a conservative about what he knows best.”

English conservatives, who are by no means confined to supporters of the Conservative party, have the best reason to be smug. Conservatism supplied the dominant version of the English national story. It helped ensure that the Conservative party was, in a phrase that said it all, “the natural party of government”.

The English, a category they could expand to cover the Scots and the Welsh, but never the Irish, have not had a revolution since the Glorious Revolution of 1688. The Glorious Revolution was glorious because it did not lead to civil war. (Ireland is always forgotten, as I said.) The country or, rather its ruling class, peacefully removed James II, a Catholic Stuart with pretensions to absolute rule, and assured the triumph of parliamentary government by replacing him with the Protestant William III.

In his speech to the (then all-male and all-wealthy) electors of Bristol in 1774, Edmund Burke explained the ideals of parliamentary government. An MP was their representative, not their delegate. He owed the voters only “his judgment; and he betrays, instead of serving you, if he sacrifices it to your opinion”.

Burke’s denunciation of the French Revolution 16 years later, heralded a further strand to the story of England as a safe, sensible nation. When Burke published Reflections on the Revolution in France in 1790, his contemporaries thought him mad to predict that an apparently benign revolution would end in “despotism”. By the time Robespierre began the reign of terror of 1793, he looked like a prophet.

Ever since then, Anglo-Saxon conservatives have been able to believe, with a smidgen of justice, that continentals had the guillotines of the 1790s and the death camps and gulags of the 1930s and 1940s because of their utopian willingness to tear up society by the roots. The pragmatic, empirical and, above all, conservative British were spared because we favoured a respect for tradition and gradual change.

Last year, Daniel Hannan, one of the leaders of the Vote Leave campaign, published a little noticed and largely absurd book, Inventing Freedom: How the English-Speaking Peoples Made the Modern World. It was absurd because the English did not invent freedom and because Hannan concluded by praising the “intellectually dazzling” Enoch Powell, the brutish enemy of the freedoms of Britain’s ethnic minorities. For all his faults, Hannan articulated the subliminal feelings of millions who voted Leave. Brussels threatened the fundamentals of national life: the rule of law, the sovereignty of parliament, the independence of the judiciary, which, in Hannan’s words, had “fended off every extremist challenge throughout the 20th century”. A decision to leave the EU would protect our best traditions.

You may not like conservatives. But you know where you are with them. Or, rather, you knew. Now, Trump, Brexit and the global rise of populism have created a crisis in conservatism across the west. You can tell a crisis is real when the men and women caught up in it duck hard questions. Today’s conservatives don’t want to say who they are and what they mean. They have become shifty operators who hate being pinned down. As Boris Johnson admitted, in one of his occasional moments of honesty, modern conservatives want to have their cake and eat it, too.

When it suits them they remain pragmatists, but that pose does not last for long. Everywhere you look you see conservatives sniffing the air and catching the scent of the radical right. It tempts them with the most seductive perfume in politics: the whiff of power. In Hungary, Poland, Turkey, South America and now, with Trump’s victory, North America, populists, who despise the checks and balances of liberal democracies, are taking control and giving every indication of holding on to it.

Conservatives have learned from Trump that they can break the old taboos. They can abuse women, damn whole races and religions, assault the constitutional order and repeat lie after lie without barely a pause for breath. Far from punishing them, the electorate will reward them. Trump’s victory is a dark liberation. Their suppressed thoughts, their guilty private conversations, now look like election winners

Don’t think it can’t happen here. Earlier this month, Ukip promised the most un-British march imaginable: a protest against the rule of law and the sovereignty of parliament. Nigel Farage warned that 100,000 people would turn out on 5 December to tell the supreme court not to endorse the high court’s ruling that parliament must be consulted before the government takes Britain out of the EU. It is never wise to believe Farage’s promises and it looks as if his march won’t happen. Protest or not, millions agree with his reasons for turning on “the establishment”. He offered his audience a stab-in-the-back myth, always at the forefront of fascist conspiracy theory, and added the equally traditional hint of violence. “Believe you me,” he said after the high court ruling, “if people in this country think that they’re going to be cheated, they’re going to be betrayed, then we will see political anger the likes of which none of us in our lifetimes have ever witnessed in this country.”

What we used to call the “Tory press” has succumbed to the seductions of the militant right. The Daily Mail called the judges “enemies of the people”, a denunciation echoed in the pages of the Sun, the Express and Telegraph. As the proprietors of the Express and Telegraph, along with the proprietor of the increasingly strange Independent, fell over themselves to welcome Farage to the Ritz last week, it would be more precise to call the “Tory press” the “Ukip press” or the “hard-right press”.

Alleged Conservative politicians are no better than alleged Conservative journalists. Everyone noticed how unwilling Theresa May and her ministers were to defend the independence of the judiciary. So much for Brexit protecting our best traditions. The facts of life in 2016 are turning out to be anything but Tory.

Conservatives would once have regarded Farage’s call for protesters to march on the supreme court as the cries of a rabble-rouser inciting the mob to intimidate her majesty’s judges. They would have remembered that Robespierre said the French Revolution owed the enemies of the people “nothing but death” and that Lenin and the Nazis agreed that “no mercy” could be shown. Whatever our politics, most of us, even now, would be confused if a Ukip supporter or rightwing journalist demanded to know if we were members of the “British people”. We might say we were British, English, Irish, Scottish or Welsh. We might say we were a citizen or subject. We ought to tell them to mind their own business. But to agree that we are members of “the people” would still sound alien to most British ears, while to hear others describe us as an “enemy of the people” would be plain sinister.

If Britain had an imperial judiciary claiming novel powers, the rage on the right would be justified. But the judges did everything a traditional conservative would have expected of them. They ruled that Burke’s representatives in the sovereign parliament must have their say on a decision that affected the rights of every British citizen. The Anglo-Saxon freedoms the Leave campaign said had “fended off every extremist challenge throughout the 20th century” were the high court’s freedoms, too. They quoted Sir Edward Coke, the Jacobean judge who defended the rights of parliament against the Stuarts. They relied on the words of the Victorian jurist AV Dicey, who said: “The judges know nothing about any will of the people except in so far as that will is expressed by an act of parliament.”

Therein lies the judges’ problem. And ours.

If you oppose the new populists you become an enemy of the people

As neo-tribalism replaces neoliberalism, you must forget about the old checks and balances democracies erected to govern complicated societies. You must be sure to respect the “will of the people” in its unmediated rawness. You must be surer still that you are a part of “the people”. For, if you are not, you can find yourself an “enemy of the people” just by carrying on as you did before.

Everywhere, authoritarian nationalists are using populism to batter their enemies. Even before the failed coup gave Recep Erdoğan the opportunity to purge anyone capable of gainsaying him, the Turkish president presented himself as the true of the voice of the Turkish people. His critics were, by definition, potential traitors.

Nicola Sturgeon and Alex Salmond have accused fellow Scots of “talking Scotland down”, for doubting the feasibility of an independent state. In a modern version of an old fallacy, nationalists hold that no true Scotsman or woman can be against the SNP. At a rally in May, Donald Trump announced: “The only important thing is the unification of the people because the other people don’t mean anything.” Trump’s supporters were “the people”. Trump’s opponents were “the other”.

Nigel Farage call Brexit a victory for ‘the real people. for the ordinary people, for the decent people’. Photograph: Frederick Florin/AFP/Getty Images

Nigel Farage called Brexit a victory for “the real people, for the ordinary people, for the decent people” The 48% who voted Remain were, like Scots who voted against independence or Americans who voted against Trump, unreal and indecent. Finland even had an authoritarian nationalist party called the “True Finns”. Its very name stated that Finns who did not support them weren’t proper Finns at all. Recently, it changed to “The Finns,” which is not much of an improvement when you think about it.

It feels cack-handed to use the “populist” label. In the west, it describes rightwing nationalists, but there are leftwing populist movements in South America, most notably Venezuela’s Chavistas, who have led their country to ruin. How can one word cover so much ground? To make matters worse, “populism” is such a soggy word. By definition, any democratic party that wins an election is more popular than its rivals. A “populist” can merely be a victor you don’t like, just as a “demagogue” can merely be an orator whose arguments defeat you. In his brilliant study, What Is Populism?, Jan-Werner Müller, of Princeton University, ties the dangling threads together. The assertion that they and they alone represent “the people” is the defining claim of modern populists. It says more about them than their superficial differences in ideology. Obviously, populists know many British, Polish, Hungarian, Venezuelan and, now, American people want nothing to do with them. But they can dismiss them as illegitimate, elitist, corrupt and treacherous. In the populist world, you are either a part of the authentic people, united as one, or you are the people’s enemy.

In these circumstances, no one in politics, the press or judiciary who takes on the populists can be legitimate. Ukip demanded the sacking of the high court judges, Trump denounced “crooked Hillary” and his supporters threatened journalists who criticised him. Farage denounced career politicians. The Five Star movement was so sure that it represented the real Italy that it said it wanted every seat in the Italian parliament because all other Italian politicians were corrupt.

Not to be outdone, Geert Wilders said the Dutch house of representatives was full of fake politicians. The limiting of the legitimate electorate to “the people” also explains populists’ repeated accusations of electoral fraud. For how can the true representatives of “the people” lose an election unless it has been rigged? That populists are the most astounding hypocrites is too obvious a point to dwell on. Farage has made a career in British politics and successive generations of Le Pens have turned French politics into a family business. When it comes to corruption, crooked Trump had to pay $25m to working- and middle-class students, who alleged he cheated them out of their savings at his phoney university. But the double standards do not worry populists or their committed supporters. The leaders of the people will pursue the people’s interests. The identity politics of the right dictates that this is the only standard you can judge them by.

I’ve already argued that Godwin’s Law cannot apply in our age. It is not only reasonable, but essential, to compare today’s rightwing authoritarianism with the authoritarianism of the past. Modern populism shares the belief of the fascists that the will of “the people” exists independently of, and often in opposition to, the views of elected representatives. But despite the shared contempt for liberal democracy and the endemic racism, modern populism remains a long way from fascism. Nor is it the same as Putin’s tyranny, although it is telling that Trump, Farage, Le Pen and Corbyn admire the Russian kleptocracy.

Populists, unlike Putin and the fascists, allow reasonably fair elections, although in Hungary and Poland they make life hard for the opposition and, with Trump’s victory, we can expect more suppression of the American black vote. You cannot rule out that fascism may come closer and voter suppression turn into mass disenfranchisement. But at the moment, it is worth noting that no European populists in power send dissidents to jail. I accept this is a small consolation.

Nor is modern populism interested in giving decision-making power to “the people”. The last thing populist leaders want is a modern version of Athenian democracy, where the engaged citizen is guiding the affairs of the state. As Müller says of the prototype for so many of this decade’s demagogic leaders, the ideal in Silvio Berlusconi’s Italy was for a supporter “comfortably to sit at home, watch TV (preferably the channels owned by Berlusconi) and leave matters of state to Il Cavaliere, who would successfully govern the country like a very large business corporation”. The same desire to keep “the people” out of politics is on show in the UK today. The old Conservative John Major says there’s a “perfectly credible case” for the people having a second vote. The supposedly people-loving populists forbid it. The “mandate” for Brexit was one vote. All the decisions that follow are no concern of the Commons, the Lords and the judiciary, say the government and the hard-right press. More tellingly, they are no concern of “the people” themselves. No one will ask them if they put staying a full member of the single market above controlling immigration. They will have no say on whether we stay in the customs union. “The people” are not allowed second thoughts. Even if inflation is rising and living standards falling in 2018, “the people” cannot change their mind. The old joke wags have made about the Nazis, Hamas and every other dictatorship that came to power by winning an election, applies to the Brexiteers: “You can only vote for them once.”

Conservatism is disappearing before the march of a new extreme right

The collapse of conservatism before this new right will be most dramatic in America. Many conservatives in the Never Trump movement honourably opposed him when he was running for the presidency Inevitably, if depressingly, the perfume of power is seducing them now he has won. In March, Mitt Romney made the best speech of his career when he warned that Trump’s policies would push the economy into recession and Muslims into the arms of Isis. If that were not enough, Trump’s “twisted” character, evident in the “bullying, the greed, the showing off, the misogyny, [and] the absurd third-grade theatrics”, made him unfit for office on its own. Romney’s fine words did not survive Trump’s victory. Last week, he was tugging his forelock and asking Trump for a job.

Jamie Kirchick, one of the leaders of the Never Trump movement in America’s rightwing press, says, as metaphor rather than parallel, that the US elite will soon be going through its version of the Gleichschaltung, the process by which German institutions accommodated themselves to Nazi rule.

In contrast, Theresa May remains a traditional conservative, but only just. The pressure she responds to comes from the new right. She shows no desire to unite the country. She has forgotten about the 48% who voted to remain and does not respond to the complaints of the many liberal members of the parliamentary Conservative party. Perhaps she, too, can smell how history is moving. If she can, she lacks the strength of character to resist.

‘Theresa May remains a traditional conservative, but only just. The pressure she responds to comes from the new right.’ Photograph: Will Oliver/EPA

The right she is listening to is becoming ever more extreme. It is easy to forget now that the campaign to leave the EU began as a traditional conservative movement to defend the sovereignty of parliament and primacy of English law. Boris Johnson, Michael Gove and the other Tories in Vote Leave avoided the taint of racism by refusing to work with Farage. Their resistance crumbled as they sensed populism’s power. By the time of the referendum, they were claiming that 76 million Turks could be on the way to the UK, with millions more Syrians and Iraqis to follow: scare stories that have, needless to say, turned out to be nonsense. If you listen to Boris Johnson or read rightwing journalists, all you find are attacks on Trump’s critics.

Intellectual cowardice explains their capitulation in part: they do not want to put themselves in a position where they upset men and women on “their side” by displaying a flicker of a critical intelligence. They just carry on as before and attack their old liberal enemies. The easy course is to join all the other conservatives sniffing the air and deciding that it is safer and more profitable to be a fellow traveller with populism than its principled opponent.

It is irresponsible to offer false grounds for optimism at this time of liberal defeat. Vast changes are coming and the British left, in particular, is in no condition to oppose them. But perhaps one day, years from now, a lesson from the left will apply to the right. In the last decade, supposedly sensible centre-left leaders said nothing as apologists for radical Islam, supporters of tyrants and the heirs of the communists came to dominate leftwing argument. So supine were they that, when the far-left moved to take over and destroy the Labour party, they could not mount one decent argument against it.

Robert Conquest’s third law of politics applies with special force to those who stand back and allow the darkness in their midst to grow: “The simplest way to explain the behaviour of any bureaucratic organisation is to assume that it is controlled by a cabal of its enemies.”

The control of a cabal of its enemies is the simplest way to explain the British Labour party. It could soon be the simplest way to explain western conservatism.

• Comments will be opened later