Evening Standard comment: The challenges for Mayor Boris

The era of Mr Livingstone's tired and compromised City Hall is over. Mr Johnson is starting to bring together a bright and experienced team. He also has the personal charm and intelligence to bring a very different style to London's governance. But all those promising signs should not obscure the scale of the task that faces him.

Crime is a major challenge. The fatal stabbing this weekend of Lyle Tulloch in Peckham is a reminder that the problem of knife and gang crime remains unresolved. It is encouraging that Mr Johnson has already engaged with the issue in a way that Mr Livingstone generally refused to. But he will have to work hard to use his limited powers - chairmanship of the Metropolitan Police Authority, and some taxraising powers - to achieve the kind of change he seeks. He has already had a constructive meeting with the Met Commissioner, Sir Ian Blair. But Sir Ian needs to be reminded that he is now on probation; he will have to prove he can deliver change. He and Mr Johnson must work together on new priorities.

And, as Mr Johnson knows, education is all-important in tackling the social exclusion that breeds gang violence. His appointment as a Deputy Mayor for Youth and Opportunity of Ray Lewis - founder of an academy to give sporting and educational opportunities to excluded youngsters - shows he understands the nature of the problem. Mr Johnson hopes that the formation of perhaps 100 Saturday clubs for problem teenagers will help offer a way of tackling the problem. His Mayor's Fund will help give moral leadership on these problems of social exclusion.

On transport, the other overriding priority, he will have to address the immediate problem posed by failed Tube maintenance operator Metronet. Its functions are due to be taken over by Transport for London but Mr Johnson must decide where to go from here. His relations with the transport unions are also of crucial importance. He wants to tie the unions to a no-strike agreement; they insist they will not forfeit their right to strike. This could result in a damaging confrontation. He should stick to his pledge to phase out bendy buses.

On congestion, Mr Johnson has rightly said that he will scrap the £25 charge on large vehicles. He needs now to explain how he can, as he promised, make the charge more flexible. But the larger transport challenge lies further ahead. The Crossrail project is absolutely crucial for London, one way its infrastructure can keep pace with population increase. Mr Johnson must fight hard to ensure that the Government does not compromise its commitment to the project.

On planning and housing, an area where he does have real power, Mr Johnson needs to demonstrate that he can strike a balance between affording the City a benign planning environment in which to allow necessary expansion and rejecting gratuitous and unsightly developments which could permanently damage the skyline. Indeed, in general, Mr Johnson must demonstrate a vision of inclusiveness, a sense he represents all Londoners - a quality his predecessor lacked. There is a curious impression among the Metropolitan elite that the "real" London is only the centre of the city rather than the suburbs. But London is both Westminster and Bromley: both have their needs and Mr Johnson must show he understands that.

Lastly, Mr Johnson must expose London's government to the light of day, sweeping away the intensely political style of Mr Livingstone. He must appoint a high-calibre chief executive with the experience of managing big budgets, and open up the decision-making processes of opaque bodies such as the London Development Agency.

The entire political climate has changed since Mr Johnson announced his candidacy last July - back then, the extent of the Prime Minister's problems had yet to become clear. To a great extent, Mr Johnson symbolises the new mood of change: he must show he is equal to the task. London has chosen well in its new Mayor. Now it is time to deliver.