Why did this week's crucial negotiating session in Belfast take so long? With Sinn Fein apparently in a position by Wednesday evening to produce an IRA commitment to decommissioning, the back of the problem seemed to most non-unionists to have been broken, and the way to have been cleared for a final resolution of the Northern Ireland problem.
Writing at a time when the fog surrounding these confused talks has begun to clear, it is difficult to assess just what made these discussions so messy.
Was the problem merely a technical one of an inability to clarify positions, or of disagreement as to who would jump first?
Was it due to unresolved divisions within the UUP ranks? Or was there, as has been suggested, a UUP game-plan of seeking to force a postponement of a decision until after the marching season?
Or were all these forces at work together?
There are, of course, people who dismiss the decommissioning issue as some kind of red herring; an invented problem, designed to cover unionist reluctance to bite the bullet of implementation of an agreed settlement.
But this seems to me less than fair. For, while undoubtedly the decommissioning issue might have been better handled by both governments and by the Northern Ireland parties, it was always going to be a critical issue.
Those who criticise the unionist hang-up on this matter must be reminded that throughout the whole history of the prolonged Northern Ireland crisis up to 1993, the stated, and firmly held, position of successive Irish governments has always been that arms must be handed over, not merely as part of any settlement involving Sinn Fein/IRA, but that such a handover should, in fact, precede any negotiation with this organisation.
Now, in retrospect this stance may be faulted as having been unrealistic, based on an inadequate understanding of republican psychology, of the likely state of mind of members of an organisation who were being asked to abandon a strategy, the pursuit of which had cost the lives of hundreds of their members. Perhaps so. But for good or ill, that was where this State stood for many decades.
Indeed, successive Irish governments were firmly opposed to, and indeed fearful of, British government contacts, whether public or secret, with Sinn Fein or the IRA in the absence of, or in advance of, evidence of a willingness of the IRA to end their violence and disarm.
Unionists were thus given every reason to believe that they would never be asked or expected to negotiate with an armed IRA or their Sinn Fein front. And that position was, indeed, formally restated in the early 1990s by Dick Spring, and echoed by John Hume.
It was not surprising therefore that the British government was disconcerted when in 1994 indirect contacts between an Irish Taoiseach and Sinn Fein/IRA led to the announcement of a unilateral ceasefire unaccompanied by any provision for IRA disarmament.
And it was not too surprising that an embattled and divided Tory government handled the outcome of this unheralded development clumsily and dilatorily, delaying the adjustment of their position on decommissioning until after the Canary Wharf bomb, and thus sending quite the wrong signal to the IRA.
The result of all this is that unionists were given every encouragement to hold on to a tough position on decommissioning, which then became subject to a disconcerting measure of progressive erosion on the part of their own government.
Against that background, it is not too surprising that unionists, preoccupied with the fears instilled in them by many decades of irredentist claims on their territory by parties and governments in this State, and since the early 1970s by a brutal campaign of terrorism, have been slow to contemplate doing what no party here has ever contemplated doing: viz serving in government with a Sinn Fein party linked to a still armed IRA.
That is the background against which the UUP stance in this week's negotiations has to be viewed. Of course, this does not mean that the UUP was either right, or wise in its own interest, to have handled the decommissioning issue in the way it has.
The fact that we all share some of the responsibility for the fact that they have found themselves in difficulties on this issue does not exempt them from all responsibility for extracting themselves from this hole, which they have clearly had difficulty in doing.
Looking back on it, it seems to me that in the negotiations of April last year, the unionists got their priorities wrong. Just as happened at Sunningdale 25 years ago they used up their negotiating ammunition on the wrong targets, on issues which it later turned out were not the really sensitive ones for their supporters.
Moreover, their over-concentration on what were to prove minor issues misled them into mistiming their final negotiating move on Holy Thursday, securing and claiming success on these minor matters at a stage that enabled Sinn Fein to move in and claim for themselves counterbalancing concessions, which then made the deal even harder to sell to unionists.
The great weakness of the Belfast Agreement from the unionist point of view lay in two features of the decommissioning provisions.
Firstly, the fact that under the agreement the timing of the formation of the executive was provided for effectively in advance of decommissioning, for which a completion date was fixed, but no commencement date.
And, secondly, the fact that the only actual commitment on decommissioning was that Sinn Fein would "use its influence" to secure its completion within two years.
The first of these provisions was designed to meet Sinn Fein's doubts about unionist good faith in relation to the establishment of the North-South institutions, the emergence of which was linked in the agreement to the creation of the executive.
And the second of these provisions was designed to cover the unwillingness of the IRA at that time to commit itself to abandoning its weapons.
On Good Friday afternoon, faced with Jeffrey Donaldson's defection, David Trimble sought some kind of cover for these weaknesses of the draft agreement and secured this in the form of a Tony Blair side letter.
But that side letter could not, of course, vary unilaterally the terms of the agreement. Consequently, it carefully said that decommissioning should, rather than must, precede the establishment of the executive.
The trouble with this ambiguous document was that it naturally tempted David Trimble to over-claim. And by so doing he got himself on a hook, from which he thereafter proved unable to detach himself. Having signed the agreement, thereafter he had no choice but to argue that it meant more than it actually did, and, until the present negotiation, he was thus effectively precluded from seeking to remedy its defects. Unhappily, all the attention of unionists seemed to remain concentrated on the issue of timing, which was always going to be very hard to modify, whereas the really important issue, upon which Trimble had a chance of success, was the fact that the IRA, which actually controls the arms, had not been directly tied into the Belfast Agreement.
An unequivocal assurance on behalf of the IRA that arms would in fact be decommissioned was something unionists could at that stage seek with credibility.
Either they received it - and could claim success - or, if they were refused it, they could justify in the eyes of the world refusing to enter the executive.
By contrast, at that stage, rightly or wrongly, no one was going to understand if they forced a breakdown on a "mere" issue of timing, a matter of a couple of months either way.
Unhappily, the timing hang-up among UUP Assembly members and supporters seemed on Thursday to make it impossible for David Trimble to jump at the offered IRA commitment, and claim victory.
Presumably it was this that forced him and his supporters to allege that they had never been offered an IRA commitment because they hadn't seen it in writing, when everyone knew that it would be available in writing if and when David Trimble told the two governments that he would be able to accept it.
The miracle is that after all that messing, something substantial was achieved last night. All credit to the two governments which together pulled it back from the brink again.
The Anglo-Irish relationship has once again demonstrated its extraordinary strength, perhaps the one and only positive outcome of 30 years of IRA violence.