This is the full version of my essay on British politics and public attitudes to immigration published last month in the International New York Times under the headline ‘A Collision with “White Van Man”‘.

Rarely can such an unremarkable photo have such heavy political repercussions. Last Thursday, a senior Labour Party member of Parliament, Emily Thornberry, tweeted a photo of a terraced house in Rochester, Kent. It showed three flags of England draped across the facade and a white van parked outside. Her caption read simply: ‘Image from #Rochester.’

This seemingly innocuous message was freighted with political meaning. By the end of the day, the tweet had become headline news, and Ms. Thornberry had lost her job as the opposition’s chief spokeswoman on legal affairs.

Why should such a banal tweet create such a political rumpus? It might help first to decode the photo for those not familiar with the nuances of British culture and politics. The flag of England (the Cross of St George) and the white van have both become symbols of working-class identity. They are, for many, markers of racism, philistinism and social conservatism. The flag is as closely associated with far-right groups and with football fans as with England as a nation. So-called ‘white-van man’ has become an archetype of the self-employed tradesman, assumed to be xenophobic, hostile to immigration and dismissive of liberal values. The phrase has the same kind of resonance as the term redneck in American culture. And like redneck, this cultural shorthand implies a snobbish contempt for the masses.

Ms Thornberry is a member of Parliament for the North London borough of Islington. In British political iconography, it stands for the liberal metropolitan elite — the polar opposite of white-van man.

The immediate context of the ill-fated tweet was a by-election in the constituency of Rochester and Strood, southeast of London. The election was triggered by the defection of the local Conservative member of Parliament, Mark Reckless, to the populist, anti-immigration U.K. Independence Party, or UKIP, whose appeal to the white-van men has caused consternation in British politics. The situation mirrored events the previous month in a constituency just across the Thames estuary, in Clacton, Essex. In a spiky by-election there, another defector to UKIP humiliated the Conservatives.

In this febrile atmosphere, Ms. Thornberry’s tweet seemed to reveal the metropolitan elite sneering at the customs and traditions of the working class. It was politically inept, certainly, but what made the affair so incendiary was not the photo itself but Labour’s response to it.

Rather than deftly dealing with an insensitive comment, the party chose to treat it as a potentially mortal blow to its electoral prospects. Labour’s leader, Ed Miliband, was reportedly ‘more angry than he has ever been in his life’. A plethora of opposition ministers lined up to condemn Ms Thornberry, seeming almost to revel in her sacking. Thanks to Labour’s clumsy handling, the story of the Rochester by-election became as much about Labour snobbery as Tory humiliation. It exposed the panic that now grips not just the Labour Party but the entire British political class.

British politics has been turned upside down as voters have deserted the established parties, while UKIP has transformed itself into a major player. (In Rochester, the Liberal Democrats, the junior party in the Conservative-led coalition government, received a derisory 349 votes.) Mainstream politicians have been left flummoxed and scrambling for answers. ‘Something is happening here but you don’t know what it is, Do you, Mr Jones?’, sang Bob Dylan half a century ago in his ‘Ballad of a Thin Man’. The same might be said today of Mr Miliband, Mr Cameron and Mr Clegg.

The scramble for answers has created an ‘arms race’ over immigration policy. UKIP’s electoral success has led the main parties to conclude that they need to raise the temperature of their rhetoric. White-van man may be a stereotype, but politicians seem to imagine that all of Britain thinks like him.

In reality, the public’s attitude is far more nuanced than they assume. A new survey of views on immigration — the result of three years of research by the think tank British Future — shows that Britons are evenly split, with about a quarter termed ‘Rejectionists’, who want sharp reductions in immigrant numbers, and another quarter who are ‘Migration Liberals’, who would like fewer restrictions. The rest of the population, about half according to the report, make up an ‘Anxious Middle’, who understand the benefits of immigration but also want reassurance that there are efficient controls. The report demolishes the assumptions that ‘public opinion is unvaryingly hostile toward immigration’ or that ‘the only way to connect with people is by ‘getting tough’ on immigration’.

Still more strikingly, Gavin Jackson of the Financial Times has found that hostility to immigration does not correspond with the presence of immigrants themselves. Plotting attitudes to immigration against the numbers of immigrants in an area, Mr Jackson found that the more migrants there are, the more pro-migration public attitudes are, too. With one or two notable exceptions, the greatest hostility is found in districts with fewer migrants.

The received wisdom is that the failure of the political elite to control immigration has corroded public trust. These findings suggest a more complex story. Instead of hostility to immigration leading to political disengagement, it may be that political disengagement is expressed through fear of immigration. So great is the distrust of politicians that when British Future researchers asked people whom they trusted in talking about immigration, more would sooner trust a migrant than any of the party leaders (including even UKIP’s leader, Nigel Farage).

All of which brings us back to Ms Thornberry’s tweet. If the furor shows the chasm between the political class and the public, it also reveals how, in their desperation to bridge that gap, politicians become even more blind to public attitudes.

Both liberals and conservatives view the public through the lens of the white-van man stereotype, imagining people to be viscerally hostile to immigration. As a result, liberals are wary of engaging with the public at all on the issue, while conservatives are convinced that draconian immigration policy can win voters’ trust. In truth, such condescension is the real problem. ‘Politicians don’t trust the public’, the British Futures report astutely observes, ‘so the public doesn’t trust them’.

The photo of the tattooed head is from Tattoobite.com.