A meeting between the Taoiseach, Mr Ahern, and the British Prime Minister, Mr Tony Blair, at a British Premiership football match in St James's Park, Newcastle, four days before Christmas precipitated yesterday's breakthrough.
The two politicians had travelled to the game between Manchester United and the local team. Five days earlier, the Castle Buildings talks had broken up, with the parties failing to secure agreement on an agenda for the post-Christmas session.
During the meeting between the two leaders after the Newcastle game, Mr Ahern told Mr Blair they must "have a go" in the new year at injecting some momentum into a talks process which had been marking time for 18 months. They decided to draw up the "heads of agreements", an outline or "road map" to an ultimate agreement.
They aimed to cover all the critical elements which would form part of the final accord which is meant to be in place in May.
According to Government sources last night, from New Year's day onwards the two men discussed the "Propositions on Heads of Agreements" by telephone; Mr Blair was in the Seychelles for part of this period and Mr Ahern was holidaying in southern Spain.
Their consultations extended to the UUP leader, Mr David Trimble, the Sinn Fein president, Mr Gerry Adams, and the deputy leader of the SDLP, Mr Seamus Mallon, when Mr John Hume was absent.
The early British draft - which was leaked to the Daily Telegraph at the weekend - had been seen and turned down by the Government before Christmas. More than six versions were exchanged between London and Dublin before final agreement was reached yesterday morning.
On Friday, a liaison group, made up of senior officials from both governments, met in London but, at the end of the discussions, it appeared there would be no agreement by the resumption of talks yesterday.
There was a lack of affinity on how to proceed; the British administration felt it should get prior agreement from each party rather than put proposals on the table.
However, by Saturday morning, both sets of officials were instructed from a political level to reach agreement on a document that could be tabled for yesterday's resumption. Sources said they had to produce something that would "shift the focus from the two weeks of violence and avoid a continuation of the political vacuum".
The Taoiseach and Minister for Foreign Affairs, Mr Andrews, as well as Minister of State Ms Liz O'Donnell - on the Irish side - and the Prime Minister, the Northern Secretary, Dr Mo Mowlam, and Mr Paul Murphy, the Minister for Political Development - on the British side - maintained contact with the other parties to ensure the final contents would be broadly acceptable.
"We did not expect the parties to sign up. We just wanted them to give the nod to the paper as a basis for further discussion," one source said.
However, it is understood that Sinn Fein did not know that the so-called Council of the Isles might be part of the ultimate document until the report appeared in the Daily Tele- graph. In the face of Sinn Fein objections, the contentious "Council of the Isles" title was dropped in favour of a general appellation, "an intergovernmental council".
It still, however, entailed the representation from devolved institutions in Scotland and Wales which Sinn Fein so disliked.
Government sources last night expressed "delight" that all the parties appeared willing to accept that this text could form a basis for future talks.
The Fine Gael leader, Mr John Bruton, said it was essential that there be "a hard centre" in the negotiations and the two governments had put this together. There had been "a very worrying period" over Christmas but, with "very good timing", both sides had moved to fill the vacuum.
"The fact of the matter is that everyone is going to have to accept less than they like," said Mr Bruton.
Welcoming the joint document, the Labour leader, Mr Ruairi Quinn, said the talks forum "is the most important vehicle to maintain the necessary momentum" and all significant developments and initiatives should be presented here.
The Democratic Left leader, Mr Proinsias De Rossa, said the publication offered "a spark of hope" after weeks of unremitting gloom. The process had always worked best when the two governments operated in tandem.
The paper seemed to offer a reasonable and realistic basis for the intensive talks that must now take place, he added.