The speed with which the emergency services responded to last week’s attack on Westminster was rivalled only by the hard right’s eagerness to blame the horror on migration. I mean, why wait for the evidence?

With the same confidence that he had (incorrectly) blamed the Berlin Christmas market atrocity on Angela Merkel’s admission of refugees, Nigel Farage told Fox News: “If you open your door to uncontrolled immigration from Middle Eastern countries you are inviting in terrorism.”

Fox News (@FoxNews) .@Nigel_Farage: “If you open your door to uncontrolled immigration from Middle Eastern countries you are inviting in terrorism.” #Hannity pic.twitter.com/p9QQgAkpbD

Arron Banks, Ukip’s former paymaster and founder of the new Patriotic Alliance, tweeted in similar vein: “Teresa [sic] May was Home Secretary for 6 year [sic] when over a million illegals were allowed into our country. I don’t think I’ve ever felt more sick.”

As we now know, the attacker, Khalid Masood, was British, born in Kent and brought up as Adrian Russell Elms. His story is one of radicalisation, the question being when and how he embraced extremist Islamist ideology: the path that led him to an act of murderous violence has nothing to do with immigration.

The lies of the right that debase civilised society | Nick Cohen Read more

Keep an eye, meanwhile, on that word “illegals”, which is gaining poisonous currency as a catch-all term for all migrants and non-white people. In his interview with the Times in January, Donald Trump used it, quite inaccurately, to describe Syrian refugees welcomed to Germany. The intended force of the word is not hard to fathom. To call someone “illegal” is to strip them of their legitimacy and brand them as – at best – second class.

This is the sharp end of a broader phenomenon in which political language is being used with pernicious elasticity. The true legacy of the fading UK Independence party is not the EU referendum or its outcome. It has been to force the politics of Enoch Powell into the mainstream and to pour all social grievances, dysfunctions and resentments into a vessel, bursting at the seams, marked “immigration”.

We are used to hearing and reading erroneous claims that migration forces Britons from the workplace; that the economy does not really need migrant labour; that migrants represent a net loss to the public purse, contributing less as taxpayers than they cost as users of public services; and that migrants are at the root of Britain’s housing crisis. It is all nonsense. But such claims, repeated again and again, have proved adhesive.

On Sunday the Sunday Times reported that, after Brexit, EU nationals already working here may continue to be paid child benefit to send home to their families. This disclosure is no doubt ill-timed for the prime minister, who will trigger article 50 on Wednesday, and unveil proposals for the “great repeal bill” on the following day. To those outraged by this probable outcome, I ask: what did you expect? That EU citizens already working quite legitimately in the UK were suddenly to have their benefits taken away to make you feel better? This would not only imperil the rights of Britons living elsewhere in the EU. It would be wrong in itself.

The broad claims of the referendum campaign are starting to dissolve into the pixelated reality of policy, practicality and compromise. According to a senior government source, a wonderful irony is now manifesting itself around the cabinet table in the contributions of Liam Fox, David Davis and Boris Johnson: “There’s no doubt that Theresa wants to bring down immigration. But the three main Brexiteers are suddenly becoming more and more vocal about the need to keep the numbers sufficiently high for the needs of the economy. You hear Liam saying: ‘We mustn’t do anything that threatens prosperity.’ It’s becoming more and more clear to them what’s at stake.”

In their defence Fox, Davis and Johnson would doubtless insist that their demand was only ever to “take back control” of immigration from the EU, rather than specifically to reduce the number of newcomers. But this was always disingenuous.

The message that the voters heard loud and clear was that escaping the grip of Brussels would mean fewer foreigners coming to Britain. As Deborah Mattinson’s fascinating Britainthinks panel surveys have shown, leave voters interpret “hard Brexit” unequivocally as being “tough on immigrants” and are uninterested in economic counter-arguments. What motivates leavers, Mattinson concludes, is “broader cultural issues”.

This qualitative research has been reinforced by quantitative findings: according to an Ipsos Mori poll in Friday’s Evening Standard, 61% regard immigration curbs as the priority in the forthcoming negotiations. A recent study by the NatCen thinktank indicated that 68% want the principle of free movement to go.

In this respect, I have absolutely no sympathy for the Brexiteers. Though they maintained the mask of respectability during the campaign, declaring that the argument was about sovereignty not immigration itself, they were perfectly well aware of the popular sentiments they were galvanising and the power of those sentiments to carry them over the finishing line.

Facebook Twitter Pinterest ‘It is becoming ever more clear that net immigration is unlikely to fall very much, if at all, as a consequence of Brexit.’ Photograph: Philip Toscano/PA

When, last June, Farage unveiled his vile poster showing a long queue of Syrian refugees under the slogan “Breaking Point”, the Vote Leave campaign distanced itself fast from the image. Well, naturally. With leaden predictability, Farage had made explicit what was meant to remain implicit. The essence of dog-whistle politics is plausible deniability – exploit bigotry, moi? – and the Ukip leader had just blown everyone’s cover.

Brexitland: People can’t find homes. No wonder they were angry | Owen Jones Read more

As the negotiations with Brussels approach, it is becoming ever more clear that net immigration is unlikely to fall very much, if at all, as a consequence of Brexit. Addressing the need for extra unskilled workers in particular sectors and regions, Davis has acknowledged: “Whatever we do has to be flexible enough to meet these requirements.” In other words: expect the new system of border control to be complex, detailed, and full of exemptions – not the red, white and blue wall that the nativists crave.

Immigration policy is a patchwork quilt and will remain so. The interdependent economy and culture of the 21st century mandate no less. But the gulf between rhetoric and reality has never been greater. As the prime minister launches the EU negotiations that will define her place in history, she faces no less a challenge at home, in managing the expectations of voters who have been grievously misled.