London has a new - and for some people unlikely - face this week. Boris Johnson, once a journalist and a former scourge of the Brussels machine, an old Etonian, former president of the Oxford Union and the Conservative MP who happily styled himself as a bit of an upper-class bumbler, begins the tough task of proving he is a worthy mayor of the UK's capital city.

As the de facto international ambassador for one of the world's leading financial centres, Mr Johnson will have to represent the multicultural capital and lead its liaison with other cities across the globe. If he can fulfil the role, it will mark one of the most extraordinary transformations in -British politics for a man who has been seen as a fervent critic of the European Union, a sceptic on climate change and a racially insensitive, gaffe-prone Conservative MP.