It is not just Ken Livingstone's reputation that is on the line

A brave experiment, of directly elected executive mayors, is already in deep, perhaps even fatal, trouble

Even allowing for the inconvenient fact that a man was injured in the extraordinary events that led up to it, Ken Livingstone's appearance yesterday before the London Assembly was classic theatre of the absurd. The first directly elected mayor of one of the world's great cities fights for his political life by describing how he rowed with his pregnant girlfriend over a false allegation that she had been smoking; how he was "jumped on" by her best friend as they left a party shortly after 1am; and how he had spent most of the previous three hours asleep because he felt tired "as I often do at parties". Then he acknowledges that he may have had "some input" into the original statement by the injured man denying that the incident was anything but an accident, a statement which he asserts was "agreed" with his girlfriend, who happens to be a member of the mayor's staff.

True, this is a conventional war rather than a nuclear one. Robin Hedges, the man who fell and later insisted he had done so after a "tussle" with Mr Livingstone, is reluctant to press charges, much as the Evening Standard, which also happens to be his employer, might like him to. Mr Livingstone is equally reluctant to sue for libel, or go to the Press Complaints Commission.

But while conventional, it is also deeply ferocious. You don't have to be in love with the strident, new-look Standard to wonder at Livingstone's wisdom in turning this into a highly personal battle with Veronica Wadley, the editor of London's only evening newspaper. Maybe one side will be able to claim a knock-out victory within weeks. But it's equally possible that the final judgement, as Mr Livingstone yesterday said it ought to be, will be left to the voters.

Either way it risks being demeaning for the office as well as for the man. It comes at a time when a brave experiment is already in deep, perhaps fatal, trouble. I can remember interviewing Tony Blair at the end of 1995 when he revealed for the first time that he was planning to introduce mayors for British cities, including London. There was a frisson of excitement. Unlike the commitments to Scottish and Welsh devolution, which he inherited without notable enthusiasm, here was something new and distinctively the Labour leader's own. And now? The Labour selection for the London candidate was a fiasco entirely of the Government's – and the Prime Minister's – own making. Two thirds of the local referendums have turned down plans for a mayor. There is unremitting hostility from councillors in many areas. In Hartlepool, the mayoralty was won by a man dressed as a monkey who promised free bananas to schoolchildren. And the Government is running good and scared; this week it announced that it was going to do nothing to encourage referendums in Bradford, Thurrock, and Birmingham.

Now the London mayoralty is engulfed in a row over what did or didn't happen at a rowdy party in Tufnell Park. Which makes it all too likely that precisely the wrong conclusions will be drawn. First, that the job cannot be made to work. And second, that the Livingstone mayoralty should be judged on this episode alone.

London was always going to be a complicated test bed for the idea of mayors. Indeed one of the worst consequences of shelving Birmingham is that it would have been a much better pilot – a big city in which the man at the top would have run a wide range of services, including education. But the Government made it much, much more complicated by hugely circumscribing the powers he could have had, including over transport. No doubt that was because it was frightened of what Livingstone might do if he won. Which makes it all the crazier that it tried to rig the Labour ballot so he wouldn't.

In fact by giving the mayoralty much less power, not only than New York or the devolved assemblies, the Government lost two possible upsides. One was that other powerful candidates than Livingstone might have come forward. The main reason that Mo Mowlam, the only figure who would, by Livingstone's own reckoning, have beaten him to the Labour nomination in a clean contest, refused to go for it, was that she regarded it as a non-job. The other consequence would have been that even if Livingstone had still won, and had had more power, voters would have been much more inclined to boot him out after one term if he had messed it up. As it is, it's rather less easy to judge his mayoralty now.

That said, one effect of the current fracas may paradoxically be to focus on what he has actually achieved. For whether outrageously, as Livingstone claims, or justifiably as the Standard unhesitatingly continued to assert yesterday, the episode can hardly fail to tarnish his congenial cheeky chap image. It's now unlikely he can get by through celebrity alone.

And here the mid-term signals are, to say the least, mixed. For the mayoralty has been rather more of a non-event than either critics or fans of Livingstone anticipated. Hardly noticed in the middle of the colourful EastEnders-style detail of the imbroglio, a survey by the London CBI yesterday found a significant majority of the city's businessmen disappointed by the mayor's performance on transport. Let's agree that the Brown-Blair-Prescott insistence on the PPP for the Tube was a piece of bloody-minded obstinacy. Let's allow – an important point – that Livingstone won the election on an anti-PPP ticket. Was it really sensible politics for Livingstone to carry on a wholesale battle against PPP at the expense of getting anything done? Particularly given that he was always going to be dependent on the Treasury for the lion's share of what he needed to make a success of London – including the grandiose development plan he announced last week. No doubt Londoners are still against the PPP. It's likelier that they are even more viscerally opposed to the long delays in getting the Tube fixed. Let's just suppose that Livingstone had said, look, I am strongly opposed to the PPP, but it's what we've got and I'll try to make it work. If it had been as unsatisfactory as he insists it is, would he have got the blame?

To be fair, Livingstone still has time – and of course his plan for congestion charges – to show he can really make a difference, provided he can extricate himself from this present mess. More importantly he will come under competitive pressure from the only plausible Tory candidate Steve Norris to deliver more than he has done so far. The character question matters in politics, and Ken's is on the line in his fight with the Standard. But the concept, as opposed to the constraints and operation, of the mayoralty need not be. Indeed the dignified scrutiny to which Livingstone was exposed by the London Assembly yesterday shows that the structure for London can work. But to keep the experiment going, the Government needs to recover its nerve and think about increasing rather than decreasing the powers in the second term. And if Livingstone wants to be the beneficiary, he will have to start delivering more than headlines.

d.macintyre@independent.co.uk