When the Belfast Agreement was signed on Good Friday 1997, British prime minster Tony Blair was moved to poetry when he said he could "feel the hand of history on our shoulders".

On Tuesday, Minister for Foreign Affairs Charlie Flanagan also reached for poetic phrasing, when describing the significance of the breakthrough which led to the Stormont House Agreement.

"It is most significant that on one of the darkest days of the winter, mid December, in the bleak midwinter, we have forged what is a broad agreement that will undoubtedly give rise to brighter days in Belfast and throughout Northern Ireland and indeed throughout the island of Ireland."

Mr Flanagan has held his post only since the Summer reshuffle, but most of his time working out of Iveagh House has involved the tortuous negotiations to break the deadlock between parties in the North that had effectively shut down government and its parliament for much of this electoral term.

Since October, Mr Flanagan has been involved in more than 100 hours of meetings during 12 weeks of involved, difficult and detailed negotiations.

It culminated with the Minister of State Seán Sherlock, and the negotiating team from the Department of Foreign Affairs, being involved in final discussions that lasted continuously for 30 hours between Monday morning and Tuesday afternoon.

Speaking to The Irish Times, Mr Flanagan said the basis of the discussions throughout was that it was all or nothing. That meant agreement on all the issues, including everything from the budget, to welfare cuts, to public sector reform, to the outstanding issues from the Richard Haas-chaired negotiations from 2013 which covered flags, parades and the past.

“Obviously the last 30 hours were quite tense in so far as the parties were in the final phase of negotiations with additions and deletions and bottom lines,” said Mr Flanagan.

On that basis, there was never certainty that agreement could be reached. "The budget was elusive until the end. There was £100 million in funding that was not certain. That involved direct discussion between Northern Ireland Secretary Theresa Villiers and David Cameron for it to be resolved.

“The other issues that went right to the wire included the past, particularly the issue on legacy inquests, as well as the North-South relations,” he said.

From a Government perspective, Mr Flanagan said, legislation will be required to give affect to some cross-border aspects of the Historical Investigations Unit, as well as the Independent Commission on Information Retrieval.

Earlier, at the joint press conference with Ms Villiers in Stormont House, Mr Flanagan said all parties were conscious that there was a high level of confidence last year for the Haass talks but they had failed.

“It is over 16 years since the signing of the Good Friday Agreement. There is a recognition among the professional politicians in Northern Ireland that matters were not functioning as they should and the system was not working.

“I believe that over the 75 heads of agreement we can go a long way towards making politics work for the people of Northern Ireland,” he said.