Since it joined the European Union in 1973, Britain's relationship with it has never been easy. But until recently, the possibility that the United Kingdom might leave has always been remote.
Not anymore. According to a report in Der Spiegel, German Chancellor Angela Merkel warned British Prime Minister David Cameron that efforts to impose immigration quotas in the U.K. would be a "point of no return" after which Berlin would no longer oppose London's withdrawal from the union.
EU countries are legally barred from limiting immigration from other member states, a decision that has had a great effect on migration patterns on the continent. In Germany, the arrival of eastern and southern Europeans in recent years has brought the country's foreign population to 7.6 million, its highest number since records began in 1967. In the U.K., the number of Polish residents increased ten-fold from 2001 to 2011, engendering opposition from Britons complaining that the new immigrants strained social services and placed downward pressure on wages.
Whether these effects are real is debatable. A study conducted this year by the University of Oxford's Migration Observatory found that immigration has a "small effect on the average wages of existing workers" and that rising wages and employment in the long run balance out temporary hardship for low-income workers. But anti-immigration sentiment has had a marked effect on British politics.