Sensible planning - Telegraph Nick Clegg, the Deputy Prime Minister, yesterday described as "apocalyptic and unhelpful" talk about what might happen in the event of a eurozone meltdown. He was responding to an interview in this newspaper with Theresa May, the Home Secretary, in which she said the Government was drawing up contingency plans in case there was a sudden influx of immigrants into Britain from elsewhere in the EU. This seems eminently sensible. Greek residents in Britain are reported to be taking up UK citizenship as an insurance policy against their country being forced out of the EU altogether. The citizens of other EU countries may do the same, regarding Britain as a safe haven because it is not in the single currency. One of the great errors of recent years was the West's failure to understand how the collapse of the Soviet Union in 1991 would trigger a massive increase in economic migration. This was compounded by the opening of borders and the greater ease of travel that accompanied the EU's Schengen agreement, from which the UK opted out in order to preserve national frontier controls. Yet that did not stop this country becoming the destination of choice for immigrants from around the world, something for which it was ill‑prepared in terms of housing, schools, hospitals and transport infrastructure. The break-up of the euro - or of the EU itself - may seem unlikely; but the same was said in the mid-Eighties about the Soviet Union and its Warsaw Pact satellites. History mocks those who think anything is set in stone. When the single currency was being set up, Mr Clegg and others who supported it scoffed at suggestions that it would cause national bankruptcy, democratic rupture and riots in the streets. All have come to pass. Any responsible government would lay plans now for every eventuality.