Supporters of Danny Kinahan roared and then burst in to a rendition of “For He’s a Jolly Good Fellow” after he ousted Rev William McCrea.
The sense of victory began building early on during Thursday night, with Mr Kinahan initially saying they faced a “neck and neck” contest.
Figures such as Trevor Clarke began to look downcast as rumours that the party was losing its grip on power in South Antrim began gaining currency.
Many onlookers stood overlooking the sports courts at the Valley Leisure Centre, counting the stacked piles of 1,000 ballot papers arranged beneath each candidate’s name and trying to work out who had more.
It appeared Mr Kinahan was gaining the edge, and at roughly 1am a party member emerged from the count room and pumped his fist with satisfaction.
However, Mr Kinahan initially refused a victory interview with the News Letter, saying he wanted to be fully sure of the result.
“I don’t dare to dream just yet,” he said.
However, around half an hour later it looked a virtual certainty, and the News Letter was the first to interview him.
He declared himself “ecstatic,” and when it was put to him that – as a liberal unionist – his ousting of comparative hard-liner Rev McCrea represented quite a change in complexion for the constituency, he said: ”Well I hope so. I’m me. I’m there for everybody. I want to really see South Antrim thriving. I don’t want to see it in those terms. I just want to see South Antrim really succeeding.”
Asked what comes next, he said simply: “Hard work.”
When the result was officially announced about 15 minutes later, there was a roar of jubilation from the UUP.
An almost bashful-looking Mr Kinahan stood amid baying backers including Mike Nesbitt himself, who had turned up to savour the victory.
Taking to the stage, Mr Kinahan thanked everyone from his wife, the PSNI for helping cover count stations, electoral workers, and the electorate at large.
“I will everything I possibly can to give you all the best, the most respectful representation that I can,” he said.
“I hope this is the beginning of a new era, a new constructive type of politics for all. And this is a great day for the Ulster Unionist Party.”
His party members then sang and clapped loudly. Pausing expectantly to hear some final words from Mr Kinahan, the newly-elected MP instead said: “I wasn’t going to say anything more!”, laughed and stood aside while Rev McCrea launched in to his speech conceding defeat.
The singing in particular may have had a particularly bitter sting for Free Presbyterian DUP stalwart Mr McCrea.
One year ago, as Diane Dodds triumphed at the European elections in the King’s Hall, he himself had led his own party colleagues in an impromptu rendition of “There’ll Always Be an Ulster”, ushering in her own victory.
Turnout: 54.48 per cent
Sinn Fein: 4,699