The killings took place just before noon: by late afternoon it was evident that the incident had succeeded in squeezing almost the last drop of optimism out of most observers and political participants. The fear is that the two murders were specifically aimed at producing an immediate loyalist backlash, a summer of violence and confrontation, the ending of the loyalist ceasefire and the disappearance of hopes for a fresh IRA cessation.
At worst, the fear is also that the leaders of the IRA have decided to impose a fundamental change of course on republicanism, dropping the aim of entry into all-party negotiations which in recent years has been one of their primary goals. If that has been put to the side, it leaves their movement with little obvious alternative but continuing and in all probability escalating terrorism.
While these are the most likely consequences of the Lurgan murders, it cannot be said with full confidence that the IRA is committed to engineering such a bleak future. In fact very little can be said with confidence because the killings have confounded the analysis of almost everyone, including both the opponents of republicanism and its sympathisers.
The puzzlement is because the IRA and Sinn Fein, in their blending of violence and politics, have generally been able to advance explanations, if not justifications, for their actions. In recent years these have been centred on the demand for entry into talks.
The 1994 cessation, it was explained, was declared by the IRA to facilitate Sinn Fein's arrival at the talks table. The February 1996 breakdown came about because for 17 months John Major refused to allow the republicans into the conference chamber. The rest of 1996 saw recurring republican violence, but this was accompanied by a further offer to John Major, which in effect he refused.
This explanation, while rejected by the Conservatives and by Unionist politicians, nonetheless gained widespread acceptance throughout nationalist Ireland and in other important power-points such as Washington. Tony Blair's accession to power thus raised hopes that a new start could now be made.
And so it seemed: Sinn Fein repeatedly set out its stall, indicating that a new ceasefire was on the cards in exchange for guaranteed entry into talks. Tony Blair and Mo Mowlam moved quickly, reopening the interrupted contacts with Sinn Fein.
Dr Mowlam publicly moved on a number of issues which had concerned Sinn Fein, downgrading the formerly pre-eminent issue of de-commissioning and indicating that she, like the republicans, was intent on designing a fast- moving talks process. Two meetings between her officials and Martin McGuinness did not go particularly well but a third was arranged even after the IRA attempted to set off a landmine in west Belfast.
Movement, momentum and engagement was the order of the day, in other words, as the government was seen to be actively tackling Sinn Fein's concerns; the logic seemed to be as the difficulties eroded a new ceasefire might not be long delayed. But the IRA has now shattered that hope of early progress, at a stroke taking two lives, laying the basis for a terrible summer and raising anew the question of whether Tony Blair can do any real business with these people.