WHEN David Cameron declared his intention last year to hold a referendum on Britain’s membership of the European Union, this newspaper gave a cautious cheer. Although we felt there was a risk the Conservative prime minister was bending too far to the Eurosceptics in his party, who happily ignore the enormous economic cost Britain would incur by leaving the union, the issue had become so divisive that we believed Britons should get a say on the subject. We were also encouraged that Mr Cameron made a rousing case for Britain’s EU membership, which he vowed to fortify and improve by campaigning for badly needed EU-wide reforms ahead of the promised vote. He needs to restate that commitment, because the recent talk from Number 10 about curbing immigration from the EU risks giving the opposite impression: of a weak and unprincipled ruling party that is prepared to gamble Britain’s national interest on a policy shaped by populists.

It’s complicated

Britain’s contradictory feelings towards immigration reflect the peculiarities of its history (see article). On the one hand, the country’s success is rooted in openness—in exploration, conquest and trade. Most Britons are not racist, which makes their country especially appealing to the millions of immigrants who have created much of its wealth. On the other hand, Britain is a bristling island nation, with a deep-seated fear of invasion. Its people worry inordinately about the economic and cultural side-effects of immigration—and are prone to scaremongers, a role which the increasingly formidable UK Independence Party (UKIP) is now filling. Its two main causes are leaving the European Union and reducing immigration.

Mr Cameron has lost one by-election to UKIP and faces the prospect of losing another in a few weeks and seeing his base eroded in a general election next spring, so it is hardly surprising that he has moved to the right. But the jump has been large and rapid. Last year, when he unveiled his EU reform strategy, Mr Cameron did not mention immigration as an area of concern. His target was red tape, not the liberal migration regime that is one of the union’s main strengths. Since then the Tories have said they want to restrict benefits to immigrants and make citizens from future EU member countries wait longer before they are allowed to work in Britain. Now Mr Cameron is talking about “fixing” immigration to Britain from the EU, while his advisers have floated the idea of an “emergency brake” on immigration beyond a certain level from even existing EU members. All will be revealed in a speech soon.

An emergency brake would be foolish in two ways. First, it is unlikely to succeed in its primary aim—fixing UKIP. A few voters may be tempted back to the Tory fold, but UKIP will always be able to outgun its rivals on promises to keep out foreigners. And most of the fears about immigration are a proxy for wider, especially economic, disgruntlements—as differences in attitudes between different bits of the country suggest. London, the city most changed by immigration, is generally relaxed about it, while several of the areas most determined to keep out immigrants, such as north-east England, have hardly seen any. An emergency brake will not assuage the anxiety in such places even if Mr Cameron could introduce it, which he probably cannot.

This is the second problem with his tactic. Free movement of labour is one of the EU’s four core freedoms. There is vanishingly little chance that other member states will concede it. And if Mr Cameron promises British voters concessions he cannot deliver, he risks not just exacerbating anti-EU feeling, but also cornering himself into a position from which he has to campaign for withdrawal from the union.

Mr Cameron started with an admirable reform agenda, which would help the whole EU. If he makes demands that will never be met he will set that agenda up for failure—and also raise the chances that vexed Britons will end up voting to leave the EU. That is a high price to pay for a few UKIP votes.