As an assailant, reportedly shouting, “this is for Syria” stabbed a fellow traveller in a London metro station last weekend, an as-yet unidentified onlooker shouted — “You ain’t no Muslim, bruv!” In the way of today, it became a hash tag almost instantly, and was used by Prime Minister David Cameron when asked about the incident after a speech he gave in the English Midlands city of Derby. Sourpusses have carped over Cameron’s upper-class accent enfolding a phrase in the patois and accent of London’s immigrant working class. But it’s been much repeated, retweeted and lauded, taken up as a defiant response of multicultural London to violence and prejudice. The incident was given a further boost when Donald Trump, picking up on the stabbing, said that there were parts of London which the metropolitan police do not patrol, for fear of radical Islamists offering them violence. A petition was already circling, with the support of more than 300,000 people, to ban the Republican front-runner from the UK. Trump owns two golf courses near the northern Scottish city of Aberdeen. (The government said it wouldn’t ban him.) Everyone of note in London denied that the police had any no-go areas. London’s witty Conservative mayor, Boris Johnson, said that “the only reason I wouldn’t go to some parts of New York is the real risk of meeting Donald Trump.” Thus was a nation united in condemnation of violence, bigotry and Trump. Creeping in below this unity of people with leaders, old with new Londoners, were two polls that received little attention. One showed that fully 25 percent of the British thought Trump was right to call for the banning of Muslims from entering the United States — a number which included 30 percent of Conservative voters, 21 percent of Labour voters and 61 percent of those who vote for the new right-wing grouping, the United Kingdom Independence Party. The second poll, for The Sun, claimed 19 percent of Muslims surveyed showed at least some sympathy for those who went to Syria to fight with jihadists. The poll roused objections immediately. What did “sympathy” mean? Which jihadists? But there was something there – especially among the 18-34-year olds surveyed, 25 percent of who expressed “some” sympathy. And another spoiler of the unity mood: several police officers said there were parts of London in which, though patrolled, they had been told not to wear uniforms while travelling to and from work. One said that Trump had “pointed out something plainly obvious, something which I think we aren’t as a nation willing to own up to.” This week is a kind of hiatus in Europe. People are waiting to see if France’s National Front, led by Marine Le Pen, can maintain its gains from last week in the second round of voting in regional elections this coming Sunday. If the center-left and -right parties agree to call on their supporters to rally round the one centrist party most likely to win in each region, the Front may be confounded, and win control nowhere. It would be down, but not out — any more than Trumpery will be out if he slips down the polls. Through midweek, though, there was little sign of it. Reuters’ tracking poll showed his call for a ban on all Muslims entering the United States has not dented his appeal. In fact, some polls showed his popularity among Republican voters had actually increased. The French mood was already sour on Muslims after the murders by jihadists of journalists at the magazine Charlie Hebdo in January. The greater bloodshed in Paris last month seems to have made it toxic, especially in many working/lower-middle-class areas. Increasingly, voices on the far right reach the mainstream, as that of Guillaume Fay, a member of the New Right and a passionate opponent of immigration, arguing that the Front “crystalizes the anguish of millions of French natives who have become progressively strangers in their own country, in the land of their fathers… they are the ones who suffer the ravages of mass immigration and mounting Islamicization… such people feel nostalgic for a France that is disappearing and where they lived well.” Nostalgia is notoriously selective, sentimental and self-indulgent, which means, it can, when widely shared, be powerful. Dependent on secular, civic values and buoyed by the success of the economies which sustained democratic states, European liberal democracies were welcoming to all — until many came. There were no great (though not empty) spaces, no recent history of nations created by immigrants, no Statue of Liberty (a gift from the people of France!) presiding over the influx of huddled masses, yearning to breathe free. The huddled masses now yearn for Europe — and it is closing against them. Under Trump, Lady Liberty would be decapitated — as a recent cartoon showed — and those yearning for America would face a new religious test. Fear is the spur. The stabbing in London; the massacre in San Bernardino; the greater bloodshed in Paris; the incessant warnings that worse is to come, combine to make Muslims living in or coming to Western societies objects of ever-deeper suspicion. That around 12,000 are killed by guns each year in the United States — a vanishingly small number of which deaths are attributable to Muslims pursuing a personal violent jihad — is beside the present point. The killings strike at the heart of US liberal generosity, a defining element in the United States’ appeal abroad and of pride in itself at home. In France, the other great Western revolutionary nation, which still proclaims its republican ideals, something of the same recoil is happening. Trump and Le Pen privilege bigotry over common purpose to oppose murder. They indict a community of believers with the crimes of their faith’s fanatics. It was comfortable to dismiss them when it was ridiculous to think they would win. But now they are winning. John Lloyd co-founded the Reuters Institute for the Study of Journalism at the University of Oxford, where he is Senior Research Fellow. Lloyd has written several books, including “What the Media Are Doing to Our Politics” (2004). He is also a contributing editor at FT and the founder of FT Magazine