Boris launches London mayor bid

Mr Johnson, Conservative MP for Henley, set out his stall at a colourful launch at County Hall in central London.

He told supporters and assembled journalists that he was campaigning for the job because "I love this city and I want it to be greater still".

At the launch, which was briefly hit by a lack of sound before his speech, Mr Johnson set out a series of pledges for London voters. These included developing a plan for 24-hour policing, securing a firm commitment to Crossrail, making the congestion charge "fairer and more flexible", and designing a new "iconic" version of the admired Routemaster bus.

In a wide-ranging speech, Mr Johnson spoke of what he considered to be some of the main concerns of Londoners, namely crime, transport and housing.

On crime, he called for a change in the culture of "casual theft and incivility on our streets". He said giving free bus passes to the under-16s was "a good idea in principle", but he wanted to ensure "we are not just turning our buses into glorified getaway cars for the minority of thieves and vandals who threaten to wreck the privilege for everybody".

His team was investigating the costs of 24-hour policing because it was then that "you build up people's basic confidence in the police presence", he said.

He declared that people should have the courage to insist on "politeness and consideration". He added: "I promise you that, as Mayor, I will be wholeheartedly on the side of the active citizen and against the thugs."

London's Congestion Charge came in for some sharp criticism, but Mr Johnson said he would not scrap it without a "better solution".

He said Londoners were in "despair", sweltering between Tube stations. He added: "We don't want any more buck-passing or blame-dodging or not-me-guv-ery. What we want is someone who will focus on getting the job done."