Tributes to his efforts were paid from almost all parts of the political compass, though Mr Mitchell issued a sobering warning as he left that many difficulties lay ahead and that both sides would have to endure "severe pain".
He urged support for the Ulster Unionist Party leader, David Trimble, in his battle to win the endorsement of his party for the outline plan agreed with the presid- ent of Sinn Fein, Gerry Adams.
The politics of the coming days will be dominated by the struggle within the Unionist Unionist Party in the run-up to the vital meeting of its ruling council, which is likely to be on 27 November. Mr Trimble has already had to disown a statement from six of his 10 Westminster MPs, in which they said this week's IRA statement was "totally inadequate".
No objections were voiced yesterday to Mr Mitchell's parting recommendation that, on a single day, power should be devolved to Northern Ireland, a new cross-community executive should be set up, and groups including the IRA should appoint representatives to discuss decommissioning.
There was speculation this might take place as early as 29 November, with supporters of the Good Friday Agreement deciding to strike while the iron is hot after what they hope will be a triumph for Mr Trimble at the Unionist council meeting.
There is some anxiety, however, among pro-agreement elements that Mr Trimble has yet to launch a full-blooded campaign to get his plan through. Yesterday he deputed other party members to make his pitch to the media.
Peter Mandelson, Secretary of State for Northern Ireland, paid particular tribute to the Ulster Unionist leader, saying: "He has driven a hard bargain indeed on behalf of his party and the people he speaks for. He has at times been frustrating, almost painful, in what he has held out for, but I must say it has shown a remarkable reward and dividend for Unionists."
Mr Mitchell had words of warning for anti-Trimble Unionists. "There has been a lot of talk about guarantees," he said. "There is one guarantee. It is that if this process fails there will be no chance whatsoever for any decommissioning. If I may use a phrase I had never heard until I came to Northern Ireland: even the dogs in the street know that there will be no decommissioning, no possibility of decommissioning, if Mr Trimble is rejected and if this process fails. Indeed, even his critics don't argue that their course of action will produce decommissioning."
The Rev Ian Paisley, leader of the Democratic Unionist Party, said Ulster Unionists had been "completely and utterly betrayed".
Meanwhile, Irish authorities have told dissident republicans they will begin seizing farms, some worth millions of pounds, which are found to house paramilitary arms dumps.Reuse content