The fact that the United Kingdom is, mercifully, outside the eurozone will not protect this country from the chill winds of recession that might be about to descend on one of our key export markets. The rapid unravelling of the 750 billion-euro fund put together just a few weeks ago to shore up the single currency has sent the markets into a spin. Mrs Merkel's precipitate ban on speculative short-selling in the German markets smacks of panic, and her rhetoric yesterday, in which she talked of the greatest challenge facing Europe since 1945, will not calm things down, even if it was designed to shock her own parliament into supporting the bail-out package when it votes today. The euro crisis could topple Mrs Merkel, due to deep resentment in Germany at being forced to rescue a Greek economy brought low by profligacy. Its medium-term consequences are still hard to discern, but might be profound. Mr Cameron may shortly discover how the best-laid plans, agreed or not, can be undone by events beyond his control.