“The economy, stupid.” An internal reminder for Bill Clinton’s presidential election team eventually became one of the most famous slogans in politics. The first President Bush was duly kicked out by the voters in the teeth of a recession, and Clinton became the 42nd president of the United States.

That is a common story. While there are exceptions, voters tend not to re-elect governments that have trashed the economy. Barack Obama’s electoral fortunes were clearly boosted by the collapse of the US economy – it is easy to forget that, before Lehman Brothers folded, John McCain had been ahead in the polls. After Northern Rock failed, Gordon Brown hesitated and then decided against calling an early election with the economy looking ropey. Unfortunately for him, it has been looking ropier ever since, along with his approval ratings.