At the weekend the happiest people in Northern Ireland were Sinn Fein and the SDLP. The Ulster Unionists were in the doldrums: they couldn't make up their minds whether they had been led up the garden path, taken for a sucker or sold a pup, on the decommissioning issue.

Fudging, ambivalence and ambiguity are not part of the official image of the sturdy, plain-speaking unionist and Orangeman. Northern nationalists would contend the image and the reality are different, but all those years of saying "No, no, no" did tend to atrophy the political skills of unionists. The decision of the British government to "go for it" when faced with the prospect of a new IRA ceasefire has changed the whole nature of politics in the North.

Despite all the sound and fury over decommissioning, the fundamental reality is that Sinn Fein and the UUP are, if not at the same table, at least in the same building. The only certain way for the UUP to remain free of contamination is to walk out and they have made it clear this is not their intention.

The vote scheduled for today on the joint decommissioning document from the two governments has been built up as a major event, yet another in the endless series of Northern Ireland cliffhangers, "DDay" for the peace process and prospects for a settlement.

Last night, however, senior UUP sources were hoping the vote could be postponed. Either way, the party is taking a low-key approach. Sources said only one representative would be sent to the talks, probably the former lord mayor of Belfast, Mr Reg Empey.

"There's no necessity for this vote to be taken. We'd rather adjourn, we're due to adjourn on July 29th anyway," UUP sources said. They insisted such a move would not necessarily disrupt the timetable for moving to substantive negotiations on September 15th - "We could have a vote at the end of August."

UUP insiders made the point that the republican movement had kept everyone waiting a long time while it made its mind up about another ceasefire, so it would be "only reasonable" to cut the unionists a bit of slack this time around.

But the main nationalist party is not disposed to make this concession to its unionist counterpart. SDLP sources were very strongly of the view that quite enough time had been devoted to the decommissioning topic, and it was time to reach a conclusion one way or another.

Besides, two weeks ago the parties in the talks had agreed to have the vote today. SDLP sources rejected the view that a defeat for the decommissioning paper would block progress to substantive negotiations.

They quoted Rule 35 of the talks procedure: "Where it does not prove possible to achieve either unanimity or sufficient consensus, the Chairman will work in consultation with the participants to remove obstacles to the reaching of agreement or, with the agreement of the participants, may decide to move on to the next item on the agenda."

It would be surprising if an astute lawyer and seasoned political practitioner like Mr George Mitchell had allowed all loopholes to progress to be sealed off.

So even a defeat of the decommissioning paper would still allow the possibility that Mr David Trimble could be "worked on". In the meantime, vote or no vote, Mr Trimble will have time to "work on" the unionist community.

The possibility of an alternative talks format, consisting of bilaterals rather than plenaries, has been mooted. At any rate, the British government has made clear its determination to press on to substantive talks on September 15th even if the unionists walk out.

The ferocity of the attack by the loyalist parties on the Rev Ian Paisley marked an escalation in the battle for the hearts and minds of working-class unionists.

Dr Paisley said the talks process was "dead in the water" although other unionists noted the DUP leader was taking a more moderate stance than they had expected and reported there was a lively debate inside both of the main unionist parties on the way forward.

There is a school of thought which believes that after today the decommissioning issue will fade and die and that in future years people will wonder what all the fuss was about. The truly historic development today may well turn out to be the presence of all parties under the one roof even if they are not at the same table.

Meanwhile, the Irish-American delegation which met Sinn Fein leaders in Belfast yesterday received strong assurances that the ceasefire was genuine and durable and that the IRA was seeking a permanent peace.

Republicans are said to be deriving comfort from the conduct of the DUP and UK Unionist Party in the talks because it deflects the charge of political extremism away from them. They were also heartened by the firm stance of the British government over the Lower Ormeau Road march and the decommissioning document.

The American businessman, Mr Bill Flynn, gave a strong hint that it would not be long before Mr Gerry Adams was received at the White House. Sinn Fein is back on the world stage.