Anthropologists will "look back in awe" at the sudden change in mood, Boris Johnson told the Conservative Party on Tuesday morning.
"A giant hormonal valve had been opened in the minds of the people," he declared to the packed conference hall. "Everyone was suffused with a Ready Brek glow of happiness." It was sunny and even the the G4S security guards "turned up from whatever they were doing".
Boris was talking, of course, about the effect on the national psyche of the Olympic Games. But he could quite easily have been talking about his effect on the mood of Conservative activists in Birmingham.
Addressing a hall as packed as it would be for a leader's speech, Boris wished Cameron well on his 46th birthday.
He told the prime minister, who was watching in the audience: "I was pleased to see that you called me a blonde-haired mop in the papers. If I am a mop, David Cameron, you are a broom - a broom that is clearing up the mess left by the Labour government, and a fantastic job you are doing.
"I congratulate you and your colleagues George Osborne the dustpan, Michael Gove the J-cloth, William Hague the sponge.
"It is the historic function of Conservative governments over the last 100 years to be the household implements on the floor of the house, so effective at clearing up after the Labour binge has got out of control."
Boris' presence loomed over the conference even before he arrived on Monday and he has tried his best to show he is supportive of the Cameron: "The prime minister and I danced Gangnam style the other day."
However he has fuelled speculation that he has his eye on the prime minister's job should the Tories lose the next election, declaring on Sunday evening that it was "unverifiable" which man would be the better leader of the party.
In his usual rambling style Boris prompted laughter as he praised the city he runs: "Every single chocolate HobNob in the world is made in London."
And as if testing his popularity to the limits he even managed to get the Tory audience to applaud his Labour nemesis Ken Livingstone for his work on the Olympics.
"I don't think Ken is going to come back from that one - he just got a clap from the Tory party conference, if that hasn't finished him, nothing will," Boris laughed.
Boris also managed to get away with an accidental pornography joke while praising "dynamic young people working in the film industry" in Soho before moving onto attack Labour.
"We've got the right government in Westminster," he said emphasising his support for Cameron. "We will fight and I will fight to keep it there. Just as we all fought together to keep London from lurching back into the grip of a cabal of bendy bus fetishists."
Who is speaking from the platform for the rest of the day?
"I literally have no idea," one young Tory shrugged on his way out of the hall after Boris finished speaking.
Pity poor Michael Gove, Theresa May and Chris Grayling for having to follow Boris. Not to mention David Cameron. Happy birthday, prime minister.