However well-intentioned it was, the catastrophic and unpopular intervention in Iraq has served in some parts of the world to discredit the very idea of western democracy. The recent collapse of the banking system, and the humiliating resort to semi-socialist solutions, has done a great deal to discredit - in some people’s eyes - the idea of free-market capitalism.

Democracy and capitalism are the two great pillars of the American idea.

To have rocked one of those pillars may be regarded as a misfortune.

To have damaged the reputation of both, at home and abroad, is a pretty stunning achievement for an American president.

Boris Johnson is the rather outspoken Mayor of London, and has opened his mouth on George W Bush: