David Cameron and Enda Kenny dealt a short, sharp shock to the Northern body politic by hightailing it out of Belfast on Friday morning.

“It was bang, bang, bang, cheerio, we’re out of here,” as one Government source succinctly put it, himself surprised that matters moved so speedily.

The question now is whether they will have any reason to return before Christmas.

The Taoiseach and British prime minister met the parties for a round table meeting at about 8.15am, and 45 minutes later they and their officials were saddling up to head south of the Border and to cross to London, chatting to the media first.

Matters had been progressing very slowly and hesitantly, and that precipitate action certainly jolted the politicians.

Word until then had been that the two leaders would stick with the negotiations until 5pm and then head home without - the expectation went - a deal being achieved and with more work to be done next week. In other words, the usual nature of politics in Northern Ireland.

Always before with the likes of Tony Blair, Gordon Brown, Bertie Ahern and Brian Cowen, talks went beyond deadlines. This time though, they didn't.

This is a different scenario: the first time Conservative-led and Fine Gael/Labour governments have been engaged in highwire talks for more than 17 years.

Brinkmanship stuggle

Previously, too, it was the likes of Sinn Féin and the DUP who tried to manage the brinkmanship struggle: this time Cameron and Kenny got their brinkmanship in first.

The premature exit seemed to have been driven by Cameron rather than Kenny. “He doesn’t seem to be a politician prepared to listen to waffle or to pander to political egos,” said a senior talks source of the British leader.

“His attitude seemed to be, ‘I am not sticking around, come back to me when you want to do business’.”

Cameron and Kenny decided on a “reality check” that instructed the politicians that we have been here before, we know what has to be done, do it or don’t do it.

In the last governments’ paper delivered on Thursday night, Cameron had outlined to the parties the financial commitments he was prepared to make to unlock movement on the other big issues such as the past, parades, flags and restructuring Stormont.

There has been movement on the past modelled on what Richard Haass achieved this time last year, but it was rejected by unionists. There has also been progress on slimming down the Executive and Assembly, and a possible fudge on flags and parades.

‘Financial firepower’

Before leaving, Cameron built up what was on offer, describing it as providing “financial firepower” of up to £1 billion over the next five to six years to the Northern Executive to offset £1.5 billion in budget cuts up to 2019.

It was also designed to get Sinn Féin and the SDLP to sign up to welfare reform.

The trouble, according to Northern Ireland's First Minister Peter Robinson and Deputy First Minister Martin McGuinness, was that the British prime minister mostly was offering the Northern Executive additional powers to raise its own loans.

It wasn't new money - "funny money" was the phrase used by Gerry Adams - when new money what the DUP, Sinn Féin, the SDLP, the Ulster Unionists and Alliance wanted.

Robinson captured rather neatly what Cameron was offering: “If he wants to bribe us, to bribe us with our own money comes a bit short.”

‘Derisory offer’

Sinn Féin Minister for Education John O’Dowd said the offer was “derisory” and described Cameron as a “penny-pinching accountant”.

Recrimination once again therefore, which will be necessary for a while to vent the poison - but it won’t get the governments or the parties anywhere closer to agreement.

So, can the parties get back in business before Christmas? Right now that seems problematic, judging particularly by what Sinn Féin are saying.

Adams seemed to be holding to the line that there might be austerity in Britain and austerity in the South, but Sinn Féin won’t tolerate any austerity in Northern Ireland: there must be no welfare cuts.

In contrast, Cameron was saying there is a different reality now: we can cushion some of the blows, but Northern Ireland can’t escape some of the financial hits that the rest of the two islands are suffering.

Which was telling Sinn Féin there is no escape from welfare change.

Still, Adams said the “game was not over”, and Cameron before leaving indicated that perhaps he could fine-tune his financial package if there was reciprocation from the other parties.

And there it lies: very serious brinkmanship that threatens the future of the Northern Executive and Assembly.