THE SPECTACULAR departure of Lord Archer yesterday from the race for the London mayoralty has transformed the contest into one that it is suddenly possible to imagine the Tories winning. Despite Lord Archer's undoubted appeal to the best-seller-reading, apolitical middle-class electorate, he was always a damaged candidate. In the end, utterly unexpectedly, it was the extraordinary events leading to his successful libel action against the Daily Star that came back to haunt him. But even if it had not been, after his self-confessed error involving the purchase of Anglia shares, and with London's only evening newspaper relentlessly opposed to him, his campaign was always going to be an uphill struggle.

Steven Norris is an altogether more disturbing prospect for Labour, as the Government has been quick to realise. For all his colourful - and never concealed - past private life, Mr Norris has style, a true feeling for London and experience as an efficient and confident minister running, among other things, the capital's transport. He has not yet been confirmed as a candidate, but it would be ludicrous for the Tories not to substitute him in the next 48 hours.

Which suddenly makes the Labour selection matter in a way that it did not through all the comi-tragic twists and turns of last week. If ever there was a time to rethink the certainties of a straight fight between Ken Livingstone and Frank Dobson, both of whom have been in their own ways damaged by those unhappy events, it is now. Time, in fact, to re- examine the merits of Glenda Jackson. Double Oscar-winning British actress (1970 and 1973). Serious politician in her own right. Clever but with the common touch, former minister to boot (and not sacked - she resigned to fight for London, and against male-dominated Millbank's wishes). A woman and, no, it is not a pity she once (or twice) undressed on screen. A feminist without being boring about it, with decent views on all the things that matter, and probably the only candidate that foreigners have ever heard of. She is very good indeed at what she did and does. Her head- girl common-sense approach even has Middle England appeal, which is more than can be said for the other two. Could Britain's capital be in better hands or have a better face - like the city itself, lived in but alive?

Ms Jackson is someone Londoners could identify with and be proud of. She has not had the media attention of the other two, but performs well in opinion polls (well ahead of Mr Dobson, on one reckoning). She has shrugged off the insult that 10 Downing Street did not think she was strong enough to stop Red Ken: hence its support for the former Health secretary. She sailed through last week's shortlist fiasco without throwing theatrical tantrums but said sensible things at the right moment. If her public persona is a little lacking in irony, it is one of her more appealing attributes that she has none of the gushing, image-conscious style of her former profession: she even admitted yesterday to being "singularly charmless". She does not manipulate or act a part, because she is confident about who she is. New Labour but not a Blair Babe; a politician, not a retired actress. Ms Jackson is her own person.

As London Labour's primary before the London presidential race approaches, there is one vital sincerity test she passes and the other two fail. Are they the same close up as at a distance? For public consumption Mr Dobson has little charisma, no studio presence, and thinks his best card is to play the bluff buffoon. Those who have worked with him privately, such as executives and top doctors in the health service, describe a different man with a clear grasp of policy and considerable administrative talent. The difference is striking and rather disturbing. Which Mr Dobson are Londoners supposed to be voting for, and why?

With Comrade Livingstone it is the opposite. He dominates the media with chirpy charm, but many of those who have worked closely with him in the past say he was a loner, a ruthless opportunist and self-publicist who, for all his posturing, is lacking in principle. One has to wonder about the integrity of a darling of the left who has agreed to campaign on a New Labour platform, which the London Labour manifesto is bound to be, save for his carefully contrived quarrel over financing the Underground (an issue that he consistently misrepresents).

The coming battle between the Livingstone and Dobson camps is a ridiculous sideshow: what a waste, what a tragedy for London that one of the most important decisions over its own future for generations has degenerated into this silly circus. London deserves a proper mayor, and Ms Jackson's name it has to be, in lights. London is lucky to have her.