Under the legislation the mayor's powers over health, for example, are minimal; but inevitably if the mayoral system is a success health, with further education, is one of the key areas where additional powers are likely to be devolved to the mayor from central government.
If a directly elected mayor had been running London's health services over the last 20 years, the direct democratic pressure of the electors would have made it impossible for any incumbent mayor to preside over the catastrophic shortage of bed spaces during every winter health crisis.
Regardless of whether the mayor had been Labour or Tory, the Conservative government would have found it much harder to maintain its attacks on the National Health Service in London. Any mayor who had ignored the health of Londoners would have been defeated when he or she came up for re-election.
The recent debate about how best to fund the modernising of London's Underground shows the real strength of having an elected mayor for London. The question of how to fund the Tube had never really broken through the wall of media indifference until this became the central issue about my suitability as a candidate, when I came up before Labour's vetting panel. Without the election for mayor, the question of funding for the Tube would have been dealt with exactly as the issue of the level of health care for Londoners was under the Conservatives.
The first four-year term of the mayor will be dominated by setting up the organisation from scratch, sorting out London's transport chaos, tackling the problems of policing in London and leading a drive in co-operation with Mo Mowlam and the Government's social exclusion unit to tackle the endemic poverty of the inner city. But by the end of his or her first term the mayor will undoubtedly be supporting legislation to devolve further powers from central government to the Greater London Authority. The mayor who takes office will have a budget of pounds 3.5bn, as compared with the budget of pounds 20bn of the mayor of New York.
In a generation's time Britain will look like the kind of modern devolved society that is the norm in continental Europe and the US, with the bulk of government at local and regional level. Tony Blair's reforms will be seen to have transformed Britain, and none more so than the new, devolved powers of the Greater London Authority.
That's why the events of the last week have been so bizarre. The decision of Shaun Woodward - the Tories' erstwhile London spokesman - to stand up to William Hague's reactionary views over Section 28 underlines what an appalling state the Tory party is now in. The bizarre collection of the walking wounded and blue-rinse nonentities who have so ecstatically thrust themselves forward to fill Jeffrey Archer's shoes must be making William Hague deeply regret his early decision not simply to allow Steven Norris to be anointed as the Tory candidate when Jeffrey Archer withdrew.
Teresa Gorman flashed briefly across the heavens, only to be consigned to oblivion by a Tory selection panel who saw her glittering trail as a portent of doom. And who can blame them, given her declared intention to turn her campaign into a holy crusade against the estimated 10 per cent of London voters who happen to be lesbian or gay?
The idea that a homophobic campaign would be acceptable in London shows just what a time-warp much of the modern Tory Party is in. The GLC caused great controversy by making a stand against discrimination against lesbians and gay men, but the ideas we then championed have now become mainstream. Were any newspaper to try to repeat the vilification and character assassination that Peter Tatchell was forced to bear during the Bermondsey by-election of 1983, it would most probably see a haemorrhaging of readers.
In the space of a decade we've moved from the situation faced by Tatchell to one where the existence of openly gay and lesbian ministers now passes without comment. The new authority will inherit a political situation very different to that of 1981. It will not be possible for the mayor to govern London without having a constant dialogue and relationship with the lesbian and gay communities.
Lesbian and gay voters will have real weight in the mayoral election. The electoral system means that every voter has two votes, with the second preferences of the other candidates redistributed where appropriate to the top two leading candidates. In such a system, the winner must gain more than 50 per cent of the vote. Estimates suggest that lesbian and gay men make up 10 per cent of this electorate - enough to make a real difference. The Greater London Authority must listen to, consult and work with lesbian and gay Londoners.
The mayor will be able to appoint members of the new Metropolitan Police Authority, including its chair. The mayor must use these powers to insist on cracking down on homophobic hate crimes and the harassment of lesbians and gay men.
The Greater London Authority will be responsible not only for its own staff but also - indirectly, through Transport for London, the fire authority and the Metropolitan Police - for thousands of employees. Indeed it will be the largest such employer in London, except for the National Health Service.
The mayor must ensure comprehensive protection against discrimination and harassment for these staff, including that on the grounds of sexual orientation, gender identity and HIV status. The mayor should also look into ways of making sure that those organisations signing contracts with the GLA pursue similar policies.
Although the mayor will not have direct powers over health, the office must be used to improve co-operation with HIV/Aids organisations and local health authorities to co-ordinate treatment and support for those with HIV.
The mayor of London will be the politician with the largest individual mandate of any politician in the United Kingdom. His is a voice that must be added to supporting repeal of Section 28 and the introduction of partnership rights for unmarried couples, including the right of same- sex partners to inherit pensions.
Even the thought of a candidate standing in London who was defending Section 28 would have been a total anomaly.