The prime ministers of Britain and Ireland flew into Belfast yesterday on an unplanned mission to save the Northern Ireland Assembly from collapse and rescue the deadlocked talks between Sinn Fein and the Democratic Unionists.
Gordon Brown and Brian Cowen last night held emergency talks with the Democratic Unionists, headed by the First Minister, Peter Robinson, and the Sinn Fein Deputy First Minister, Martin McGuinness.
Their joint intervention came after a lunchtime meeting between Mr Robinson and Mr McGuinness which was so terse that it lasted well under an hour. Defined in advance by Sinn Fein as "defining and critical", it clearly served only to confirm that the two parties were at an impasse.
They appear to be at loggerheads over some of the technicalities of the transfer to Belfast of responsibility for policing and justice.
Sinn Fein, together with London and Dublin, want this to take place immediately, but the DUP has insisted that it must first ensure that sufficient confidence exists in the Protestant community.
In terms of the present ongoing negotiation, this means changes to the regulation of parades, chiefly those of the Orange Order. A senior Orangeman has recently appeared on the DUP negotiating team.
Sinn Fein has protested that parading has nothing to do with policing, complaining that the Orange Order's aim is to go through Catholic areas without consulting local residents.
Following the Robinson-McGuinness lunchtime meeting, the two prime ministers, who had been meeting in London, boarded a flight to Belfast.
The general sense is that the DUP and Sinn Fein have spent months demonstrating beyond doubt that they cannot reach a deal unaided. This does not necessarily mean, however, that agreement is beyond reach if London and Dublin weigh in together.
The prime ministers will therefore be cajoling and pressurising the Belfast-based parties to find compromises to get the peace process through this present crisis and keep the devolution show on the road.
In this instance most of the pressure will be applied to Mr Robinson to drop his opposition to rapid policing devolution. The main point of leverage on him is the possibility that a breakdown would lead to fresh Assembly elections in which his vote would slump. The DUP is the largest party in the Assembly, but all the predictions are that voters would punish it severely for the Iris Robinson affair, which has attracted hugely damaging publicity for the party.
A sharp fall in the DUP vote could well leave Sinn Fein as the largest party, which would give Martin McGuinness first call on the post of First Minister. That could lead to political turmoil, but in the short term it would probably mean the end of Mr Robinson's term as DUP leader.
Mr Brown said yesterday: "We believe that the problems that exist in devolving policing and justice are soluble problems. We believe it is right to move forward in this way and we believe that together we can assist in the completion of these talks."