On the evening of 7 May 2015, Vince Cable watched coverage of the general election at home. For more than two decades, he had been a Liberal Democrat MP for Twickenham; since 2010, a member of the cabinet, too. In the coalition government he was a long-serving business secretary, president of the board of trade and a privy councillor. Cable ran a constituency office, one in parliament and a major Whitehall department. He was responsible for thousands of staffers, plus a whole host of junior ministers.
Then, quite suddenly, he was not.