Boris Johnson wants to be taken seriously. Don’t laugh. That would ruin everything. For that was Boris’s one big goal yesterday as he launched his campaign to be London mayor. He had spent all summer learning to be tedious and, for his launch, he had prepared an earnest promotional film and a speech full of policy insights. It was going to be a triumph of dullness.

That, at least, was the idea. The event was held at the old County Hall, in the former chamber of Greater London Council. For the day, the circular chamber was bedecked with BACK BORIS posters. We sat in the aged leather seats, some patched with duct tape, and listened to London Calling by the Clash, Waterloo Sunset by the Kinks and The Streets of London by Ralph McTell. I’m sure you see a theme emerging there.

Bizarrely, the event began with a woman shouting at us about the “emergency procedure” for getting out of the building. It was like being on an aircraft and being told to hug our cushion when we crash-land on water. It was not comforting.

A Tory called Mr Cleverly introduced Boris, the Movie. The screen flickered on with dynamic footage of people rushing around London. There was no sound. Was it a silent movie? Was it arty? Then Boris appeared, on Parliament Hill in front of what appeared to be a group of cows, mouthing something at us. Perhaps this was some sort of Charlie Chaplin tribute.

The movie screeched to a halt. Mr Cleverly was back, living up to his name. “Don’t worry, this will all be edited out from the final cinema release!” Then, after a judder or two, Boris, the Movie returned, with sound. It was a let down, for the silent version was so much better. The sound version was all about transport, housing and why we should all go to the V&A.

Afterwards, Mr Cleverly returned to introduce the man himself: “I give you the the original political blond bombshell!”

Boris bounced in through the exit (the one we had to go through in case of an emergency), his hair whirly-gigging around his head. He may have tried to control it with hairspray but it was futile. Boris, the Man, was far more entertaining than Boris, the Movie, although I don’t think he meant to be.

He kept making stabs at being serious. At one point, he actually quoted GDP figures. But then he would blurt out statements like this: “I see fantastic improvements on the London of my childhood. I would never have dreamt that you could go to a newsagent and buy mango juice. We had never heard of a Frappuccino.” Is that a slogan that can work? Mango juice for the masses? Frappuccinos not for the few but for the many?

He has lots of big ideas (none bigger than decoy bikes to catch thieves, though) and was scathing about Ken Livingstone and his dealings with Hugo Chávez of Venezuela. “You won’t catch me doing deals with left-wing dictators,” cried Boris, “which means that Venezuelan slum children are effectively subsidising Transport for London. I say that is completely Caracas!”

Caracas. ¡Ay caramba! It was a joke. The crowd went wild. Boris was immediately hit by pangs of guilt. “I reserve the right, by the way, in the course of this campaign, to make jokes!” he noted defensively. “But be in no doubt that I am deeply serious in this campaign.” Oh, I do hope not.

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