Confirmation that the IRA has opened a number of arms dumps to inspection was greeted with relief in British circles yesterday, but with some surprise in nationalist quarters.
The seemingly fierce debate over the Patten proposals for the reform of the Royal Ulster Constabulary - and the failure of the British government Police (Northern Ireland) Bill to fully reflect them - had cast a question mark over the timing of the IRA's promised "confidence-building measure".
Mr Peter Mandelson, who frequently now identifies a certain "rugged honesty" about IRA statements and commitments, had maintained public confidence that the republicans would deliver on their side of the May 5th deal.
Others in the British establishment were not so sure. Certainly, until Friday, ministers were privately anxious lest the IRA should choose to delay and play it long.
Leading nationalists, too, were sceptical about Mr David Trimble's apparent certainty that the republican initiative - both the opening of arms dumps to inspection and the reappointment of interlocutors with Gen de Chastelain's International Commission - would come before the expiry of the notional "deadline" of June 30th.
The furore over Patten was the obvious reason for the scepticism. Unionists see the SDLP and Sinn Fein as being in something of a competition over policing. Each has criticised the Police Bill, claiming that the "gutting" of the Patten report has the potential to cause a serious crisis in the peace process.
The Catholic Hierarchy and some members of the Patten Commission have echoed those concerns.
Mr Seamus Mallon, deputy leader of the SDLP, surprised many people when he led his colleagues, Mr John Hume and Mr Eddie McGrady, into the government lobby to support the Bill at Second Reading. Despite this, during the ongoing Committee Stage Mr Mallon has repeated his warning that unless Patten is restored the SDLP will not sit on the new Policing Board or advise young Catholics to join the new police service.
And, despite assurances about Mr Mandelson's intention to be faithful to Patten, Sinn Fein spokesmen have said they will reserve judgment until they see the finished product.
The knowledge that the Bill will not complete its parliamentary passage until the autumn fed the anxiety that the IRA might delay its promised action until then, with all the attendant risks that would have entailed for Mr Trimble.
The Ulster Unionist leader has had to reconcile himself to Mr David Burnside's selection as UUP candidate in the South Antrim by-election, which will probably take place in September. But Mr Burnside's talk of uniting both wings of Ulster Unionism would have been challenged seriously by the continued absence of the IRA's "confidence-building measure" at that point.
The fear in some UUP circles was that victory for him on an ever more specific anti-agreement ticket - or, worse still, defeat at the hands of the DUP - could have provided the springboard for a fresh assault on Mr Trimble's position at his party's conference in October.
As it is, Mr Burnside's unity theme may not survive the tests of time and the imperatives of getting himself elected. Certainly he, Mr Trimble and the Ulster Unionists have a long way to go until September.
The DUP is believed to have the requisite signatures to force a debate on the exclusion of Sinn Fein from office. Drumcree looms ever closer. And Mr Jeffrey Donaldson was quick off the mark in insisting that the IRA's actions do not constitute decommissioning in conformity with the legislative provisions.
Mr Ken Maginnis acknowledged his own, and Mr Trimble's, difficulty yesterday. He described the IRA statement as an encouraging development, but in a context where republicans still appeared to be facing both ways on the arms issue. Those responsible for the murder of Mr Edmund McCoy have yet to be identified, while two men appeared in court yesterday in connection with last week's pre mature explosion of a device in west Belfast.
Over and beyond that, pro- as well as anti-agreement unionists have obvious questions about the process now begun by Mr Cyril Ramaphosa and Mr Martti Ahtisaari.
Intriguingly, their statement expressed confidence that the weapons inspected (presumably in the Republic) could not now be moved without their knowledge. This would seem to imply that republicans have agreed a means by which both sides can verify the continuing security of these weapons dumps, whether by way of electronic surveillance or other means.
That would certainly strengthen the already widespread perception that this exercise is indeed "historic" in the Irish republican context.
As he and his leader had conspicuously failed to create a public clamour for the IRA initiative - lest they be seen to make life difficult for the republican leadership - so yesterday Mr Maginnis took care to recognise the value of the progress made thus far.
From Mr Tony Blair, too, there was expressed pleasure that "the agreement that was made a few weeks ago has been honoured". There was certainly nothing niggardly about the British response. In the prevailing climate, Mr Donaldson might have struck some as predictably ungenerous in insisting that this marked but a first step.
However, the Prime Minister's words also provided a corrective to the initial impression given by the Taoiseach that the decommissioning issue had now been dealt with. "The whole process of decommissioning has to be gone through", Mr Blair said. "This is a confidence-building measure. It is not decommissioning itself. It is a step on the way."
Not the end of history, then, but a significant step nonetheless.
The fact that Mr Mandelson has yet to pronounce on key issues such as the title and emblems of the new police service, and the flying of the Union flag, makes it the more surprising - and, possibly, the more significant - that the IRA has acted at this time. So surprising, indeed, as to persuade some insiders that the battle over Patten itself could already be over.