It wasn't the most auspicious beginning. David Trimble was on the stage of the Waterfront Hall, preparing to fight for his political life, when he realised the overhead projector was broken.
There was no way for delegates to see his motion, which had taken days to prepare and finetune. His supporters were aghast. The UUP leader started to panic. "Trimble is flapping around in an awful state," said a delegate.
A worried collection of UUP officials gathered around the projector but to no avail. "It's like the feminists and the light-bulb," chuckled an anti-agreement member.
Things could only get better, and they did. Mr Trimble gave a solid performance. There were strong speeches from Jim Nicholson MEP and Sir Reg Empey. But the No camp was quietly confident.
The UUP deputy leader, Mr John Taylor, is regarded as a party weather vane. "John sees what way the wind is blowing and blows accordingly," said a delegate. Earlier in the week, Mr Taylor had said there was some "merit" in Jeffrey Donaldson's proposals.
Now, he was nowhere to be seen. Without his deputy by his side, Mr Trimble looked vulnerable. Wild rumours circulated of Mr Taylor's whereabouts. Some thought he was in Lithuania. There were reported sightings in Italy.
As the meeting progressed, the Trimble camp's confidence grew. UUP officials relaxed over coffee, cigars and apple strudel.
The Donaldson team looked worried. The level of applause in the hall for various speakers didn't favour them.
"Judging by the clapometer, we will lose," one said. He went off to urge Mr Donaldson to accept a compromise motion.
Somebody else disputed that reading of the clapometer. "It depends where you're sitting," he said. The meeting broke for 15 minutes.
There were reports of private Trimble-Donaldson talks but there was no compromise. "The two beauties are going head-to-head," somebody said. One delegate complained of the queue of speakers still waiting to be heard.
"If this keeps up the decommissioning deadline will have passed", he said. As voting began, the mood in the No camp changed dramatically. By their own calculations, they were ahead. "I think we've got it," confided a Donaldson aide.
Trimble's people looked worried. A huge press contingent gathered outside. Dozens of cameras were trained on the hall's doors. Then the result came. Mr Trimble had triumphed by 71 votes. "We have lanced the Donaldson boil," a UUP official said.
Outside, anti-agreement protesters jeered as Mr Trimble left the Waterfront. "A vote for David Trimble is a vote for the IRA!" they yelled.
The UUP leader drove off for a victory drink in TaTu, one of Belfast's trendiest new bars. His team looked exhausted but relieved.
"It's been a hell of a day," one said.