There was an unmistakable sense of excitement at Conservative HQ this morning as Boris Johnson was formally confirmed as the party's mayoral candidate.

That excitement was not from any party loyalists bussed in to provide fake jollity. It came from the gaggle of wizened journalists and grizzled photographers freezing outside Millbank tower.

They know that if Boris lasts the pace then we will have a mayoral election that promises to be even more exciting than the inaugural race in 2000. That, of course, was the one in which Jeffrey Archer was replaced as the Tory candidate after he admitted lying to a libel trial, and when Ken Livingstone, standing as an independent, triumphed against the Labour machine after being denied the chance to be the party's official candidate.

As a journalist himself, Boris knows how to play (and attempt to control) the media. His adoption today was simply a sign that the Tory party had not shot itself in the foot. Only 1,000 "normal" Londoners - and around 19,000 party members voted - well below expectations. But the process will quickly be forgotten. It has served to move the Boris bandwagon up another gear and should minimise the risk of dissension in the Tory ranks.

Accompanied by party leader David Cameron and chairwoman Caroline Spelman, Boris made his winner's speech to an excitable room of Tory borough leaders. Only the Evening Standard, and cameramen from Sky News and the Press Association, were allowed inside. No questions were allowed.

The empire of Ken - or "King Newt" as Boris dubbed him in his press release - was ready to fall, they were told. Boris pledged to recruit "all the talent and expertise" of the boroughs to the fight. Council leaders licked their lips at the prospect of joining a Boris cabinet. Maybe Boris would run London like Michael Bloomberg does New York, with a series of deputy mayors being handed weighty portfolios. Handily enough, Mayor Bloomberg will be at Tory party conference on Sunday - the day of Boris's big speech.

Outside, the rest of the media were kept waiting. Boris and David Cameron emerged for a two-minute photocall in front of Boris's battlebus (a battered Routemaster). But there was enough for everybody. And the shots of Boris waving from the open rear deck as the bus pootered off down Millbank brought laughter as his "magical mystery tour" resumed in earnest.

Earlier, the morning began with Boris finally braving an interview on the Today programme. He emerged bruised but unbroken after a battle with Jim Naughtie. He escaped the charge that he was not a serious politician. And he finally made clear that he would not remain an MP if he were elected Mayor.

However we had to wait for another radio interview, this time with LBC's James O'Brien, to be sure quite when Boris might quit his Henley constituency. "I will be giving up my seat in the House of Commons if and when I become elected," he said. Of course, this will leave him in a bind - and without the safety net of a backbencher's salary - if Gordon Brown calls an early election.

Back at City Hall, there was uncharacteristic silence. There have been plenty of Boris insults at Labour party conference - including a good joke from Ken about making "the first annual Boris Johnson memorial lecture". But the only missive was about the Mayor's wish to make affordable housing more accessible for disabled and deaf Londoners. Yesterday Ken was given a hero's welcome at party conference. Today belonged to Boris.

On Thursday morning, the Tories will unveil their candidate to take on Ken Livingstone in next year's mayoral elections. Barring a major shock it will be the blond bombshell that is Boris Johnson. He undoubtedly has the star quality that threatens to put even Ken Livingstone in the shade. But observers of the Tory hustings have seen a different Boris than the one who became famous for his hilarious appearances on Have I Got News For You.

At each of the hustings I attended - Lambeth, Ilford and Sidcup - Boris started with a five-minute presentation, delivered at the breakneck speed of a Eurostar from St Pancras. But as the questions began, he slowed to the pace of the North London Line as each evening became bogged down in the bread and butter of municipal politics.

And it was here that his lack of London knowledge was most evident. His rivals Warwick Lightfoot, Andrew Boff and Victoria Borwick have considerable experience in borough politics. Boris may live in London but he does not know the city like Ken does. He railed against the "Neanderthal trade unionism of the RMT", promised to remove free bus passes from teenage hoodlums and would scrap The Londoner, Ken's free propaganda sheet that costs in excess of £3 million a year to publish. All are obvious targets but hardly show fresh thinking.

Boris was careful not to stray from the shadow cabinet line on the London Olympics (insulting Lord Coe would not endear him to the hierarchy) or the environment. The £20-a-year average contribution from a London household towards the 2012 preparations must not increase, he said. He was forced to perform a crafty sidestep when one questioner, in a bid to scupper David Cameron's "green" agenda, demanded the Tories place crime and family welfare above climate change in their priorities.

"We will win the general election by concentrating on the issues that matter most directly to people's lives," Boris said. "That is improving schools and making sure crime comes down. But we won't win unless we address people's anxieties about the environment. It's a profound Conservative instinct to want to pass on this land in pretty good shape from one generation to the next."

But his eyes glazed over when asked what he thought about inconsequential matters such as transport on the Thames and rickshaws (or Tuc-Tucs) in the West End. He was right about planning, though, where new legislation will make it easier for the Mayor to overrule the boroughs - this, he said, had the makings of a major campaign around which the capital's Tories could unite.

"We need to save the suburbs from Ken Livingstone," he said. "If we can get that message across we should win."

The hustings provided a valuable insight into the strengths and weaknesses of the four candidates. The three relative unknowns all acquitted themselves well - and at the very least would energise the tired Tory contingent on the London Assembly. Warwick Lightfoot, many media observers noted privately, has the makings of a very considerable figure in London Tory politics. The tragedy is that they were so poorly publicised. The party leadership wanted all Londoners to participate in the debate. Yet only around 120 poor souls made it to Ilford and a woeful 50 to Sidcup - in what should be solid Tory territory.

Ken Livingstone is known to have had observers at at least one of the hustings, and will have been delighted at Boris's "knowledge gap". If there were an election next week, Londoners would face the choice of a wise old head versus the young pretender. Who would you trust to sort out the Tube? Or, perish the thought, to speak for the city in the event of another terrorist atrocity?

Boris's attractions are obvious to those who want Ken out, those who want to treat the election as a joke and those who would enjoy sticking up two fingers to the establishment - ironically, he is the kind of rebel candidate Ken himself was eight years ago. For those who think more deeply, Ken is in pole position.

But the election is not next week, but next May. Boris will have plenty of time to do his homework. He can do "the showbiz" every bit as well as Ken. If he can mobilise all London Tories to vote for him - something Steve Norris failed to do - a mass of fun-loving young Londoners who would not typically vote plus the all important second-preference votes, Ken could be a worried man next May.

ends

Ross Lydall is City Hall Editor of the Evening Standard. He has been writing about Ken Livingstone, the London Olympics and the congestion charge since 2002. He also writes the Inside City Hall diary column, which appears in the paper most Fridays. His blog will aim to bring you all the news and gossip from the forthcoming 2008 mayoral race. You can contact him at ross.lydall@standard.co.uk.