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.