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On a recent visit to Washington, a top British diplomat began his presentation to American colleagues by assuring them that there is no way that Britain will leave the EU. His declaration had the opposite of the intended effect. “Until that,” said one of the Americans present, “it had never occurred to us that Britain would leave. Now we’re really worried.” In fact, everybody should calm down. The threat of Britain actually quitting the EU remains small. The current atmosphere of crisis is real enough. But once you start thinking through the likely chain of events, continued British membership of the EU remains easily the most probable outcome.