It was the sign everyone in Guildhall Square was waiting for - but it came in a manner they would never have expected.
As thousands watched the Guildhall clock edge towards half-past three, a copy of the Saville Report appeared at the window.
It was followed by an unknown hand - and the thumbs-up.
The square erupted with cheering, shouting, and clappping.
Nobody watching knew what was in the Saville Report, nobody knew what the Prime Minister was going to say, but everybody there knew the contents of the report would be what they wanted.
And it was. A screen erected to the side of the Guildhall showed live coverage of David Cameron's speech in Westminster.
The crowd kept cheering - when he said Bloody Sunday was "unjustified and unjustifiable"; when he said the Army fired the first shot; when he said there was no justification for the soldiers' shooting.
There were boos, too, when David Cameron praised the army's record in Northern Ireland, and described British soldiers as "the finest in the world".
Some of those I could hear around me didn't think it was going to happen. "See, he's not going to apologise", went one overheard conversation... and then suddenly, the mood changed. He was going to apologise.
On behalf of the government and the country, "I am deeply sorry," he said.
For a moment, there was nothing to be heard but the sound of celebration.
The cheers got louder when the families emerged, hands raised aloft, some waving copies of the report.
The word "innocent" reverberated around the square, repeated after the name of each victim and each of the wounded.
As Tony Doherty, whose father Paddy was killed on Bloody Sunday, told the waiting crowd: "These are the words we've been waiting for. The truth has been brought home at last."
"We always knew my brother was innocent," said the sister of William Nash, "but now the world knows."
Earlier thousands of people converged at the Bloody Sunday memorial to walk to the Guildhall, symbolically completing the march which was prevented from reaching its destination 38 years ago.
From every street and road and estate, people were coming - and they kept on coming.
It was a case of people physically showing their support not just for the Bloody Sunday families, but also for their long quest for to have their loved ones' names cleared.
As one woman, Deirdre Carlin, put it: "Bloody Sunday was the day that kicked it off, that filled the graves and the prisons on both sides. I'm not surprised there are so many people here."
Their faith was repaid. Taking the podium outside the Guildhall on behalf of the Bloody Sunday families, Mickey McKinney was just the first relative to publicly thank the people of Derry for their support.
"This was a traumatic time for the families," he said, "and we could not have done this without your help and support.
"We know we stand here today among friends.
"This is a historic day for Derry - and of all people, I'm entitled to say it."