He banned bendy buses but brought in Boris's bikes - as London prepares for the mayoral vote, Channel 4 News assesses the achievements of the incumbent, affectionately known as BoJo.
Boris Johnson was catapulted into City Hall in 2008 with a majority of 150,000 first preference votes. His popularity in the outer suburbs helped oust the capital's inaugural elected mayor, Ken Livingstone. Although he is a well-known and instantly recognisable figure, Boris Johnson's critics say he has not stamped his personality on the mayoralty in the way that his predecessor did.
Blogger and journalist Adam Bienkov assesses Boris as a man who has made "lots of small achievements but has never had much of a grand vision".
Whereas Mr Livingstone famously established the congestion charge zone (whereby motorists pay a daily fee of at least £10 to use their vehicles in central London,) in a bid to ease the capital's clogged streets and reduce pollution, Boris won a popular following, especially in the outer boroughs of Bexley and Bromley, by cutting the size of the zone.
His much publicised cycle hire scheme, dubbed Boris Bikes, is a visible legacy on streets around London. But Transport for London's own figures show the scheme is used by fewer than 1 per cent of Londoners with a core constituency of high-earning men aged between 25-44. This scheme was already being planned when Johnson took charge however, so its success or failure is not entirely of Boris' doing.
Under the mayor's leadership bus fares have also increased by 50 per cent, a change which has had more of an impact on the poorest Londoners unable to afford Tube fares and those living in areas, mainly south of the river, not well-served by the underground network.
According to Adam Bienkov, Mr Johnson has turned out to be a more centrist mayor than might be expected from someone seen as an almost archetypal Conservative politician: "I think a lot of people thought he'd be a very Conservative mayor but he's actually turned out to be a kind of Ken-lite figure.
"He hasn't really made City Hall his own. London is a pretty left-leaning city and he's had to fit in with that. City Hall was created in Ken's image and you need to be a strong personality to make your mark on it and I don't think Boris has that.
Somebody like Steven Norris would probably have had a much bigger impact on London and made a very different sort of Conservative mayor. Adam Bienkov
"Somebody like Steven Norris would probably have had a much bigger impact on London and made a very different sort of Conservative mayor."
So what does the man himself think he has achieved? The Back Boris website points to significant drops in crime, especially serious crime such as murder. It says that crime overall has dropped by more than 10 per cent since Mr Johnson took up residence in City Hall.
Mr Johnson points to having quadrupled the capital's rape crisis centre provision, but Metropolitan Police figures show the number of rapes in the capital between January 2011 and January 2012 went up by 5 per cent.
The long-awaited Crossrail project was also begun on Boris' watch, though the delays in approving the scheme could as easily be blamed on central as local government.
It is hard to predict what will be the impact of the Boris mayoralty on May's election - at the moment the poll is running neck and neck.
There is still time for either side to pull ahead, but the lack of a clear lead for either of the main candidates suggests a huge amount of PR is needed to convince London's electorate of who is the best person for the job.
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