Enter the van men

ADVERTISEMENTS displaying handcuffs and a phone number are a hoary staple of Britain’s provincial media. Most concern dominatrixes. But the billboards circulating in outer London neighbourhoods in recent weeks have a fiercer function. Mounted on the back of vans, they convey a message from the Home Office urging illegal immigrants to “go home or face arrest”. By dialling the number, the individuals in question can obtain advice and help with travel documents. Not many are expected to take up the offer.

News of the ruse sparked a row in Britain’s governing coalition. The Conservative Party, whose ministers approved the measure, cheered loudly. The Liberal Democrats were horrified, denying prior knowledge and calling the campaign (in the words of Vince Cable, the business secretary) “stupid and offensive”.

A backwards glance puts the spat in perspective. Last summer the two parties were emerging from their noisiest argument since 2010. Conservative backbenchers had just wrecked a Lib Dem bid to reform the House of Lords. In return Nick Clegg, the Lib Dem leader, had stymied changes to electoral boundaries that would have helped the Tories. The mood among backbenchers was foul. Talk of leadership coups abounded.

Today, however, both David Cameron and Mr Clegg—and with them, the coalition—look safer. Both parties have risen in polls, their ranks are more contented. The squabble over the “go home” van explains why: each has developed a clearer message about what it stands for.

Starting with Mr Cameron’s conference speech in October, the Conservatives found a new, tougher voice. The party has woven the three policies that it believes will win it the next election—reducing immigration, cutting benefits and reviving the economy—into a paean to Britain’s “hardworking people”. Under Lynton Crosby, an Australian strategist hired in November 2012 to prepare the party for the election, this message has become yet crisper. “Barnacles”, as Mr Crosby calls irrelevant or distracting policies, have been stripped from the boat. In their place are “wedges”—contentious policies precision-engineered to put the opposition on the wrong side of popular opinion. The immigration vans—draconian, gimmicky and popular—were one such example.

Though they decried it, the policy helped the Lib Dems too. Their strategists divide the five-year coalition into three phases—unity, differentiation and divergence. Moving from the second to the third of these, they have planted their flag in favoured policies (green energy, a higher income tax threshold and new support for poorer pupils) and claimed to moderate Tory excess. The van dispute enabled them to do so: Mr Clegg boasted that he had told the Conservative immigration minister to concentrate on border checks instead.

More is to follow. The home secretary, Theresa May, and the welfare secretary, Iain Duncan Smith, both Tories, are planning tough announcements for the coming weeks. The Lib Dems will circulate a self-congratulatory policy report alleging that their partners “can’t be trusted to build a fairer society”. Despite this, the coalition will hold together. Sporadic explosions are mostly controlled—co-ordinated at the top of government, where relations are still remarkably cordial, but designed to distinguish the two parties in the eyes of backbenchers and voters.

Moves like the immigration gimmick contrast with the bold, turbulent overhauls of public services and state finances that dominated the first half of the parliament. The latest Queen’s Speech was dispiritingly bare; symbolic show-squabbles, stunts and electoral posturing look set to dominate the run-up to the 2015 election. Two years of placid bickering and legislative indolence await.