Ukip once more proved it is a force to be reckoned with by pushing the Conservatives into third place in a by-election last week. It is credited with shifting the political ground rightwards, but can it reap prizes of its own in the bigger challenges to come? A question political observers in Britain often ask is, with which of the party leaders would voters most like to go for a drink? And in an age when the three “main” political parties are led by men who all came of age advising senior politicians, the answer today appears to be the outsider, Nigel Farage.It is true that the United Kingdom Independence Party (Ukip) leader, a former stockbroker with the air of a used-car ­salesman, is convivial company. When I ­interviewed him in 2012 over a pint at the Marquis of