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 the 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.