Britain is getting used to political gamblers. David Cameron held a referendum and Theresa May hoped Brexit would allow her to steal Labour territory and win a huge majority. They both failed, and join Margaret Thatcher and John Major as the four Conservative prime ministers brought down by Europe.

Boris Johnson could be the fifth. With a majority of just one, after the resurgent Liberal Democrats triumphed at the Brecon and Radnorshire by-election last week, the word in Westminster is that either a vote of confidence will be called early next month or Johnson will push for a snap election after delivering Brexit. Either way, if he is to triumph over Europe then he, too, will need to place a bet — that he