Labour figures said it was the first appearance in recent memory of an Opposition front-bencher at such an occasion and had cemented Labour's more "inclusive" approach towards the Unionists.
Since July 1993 the nine Unionists have voted regularly with the Government, but Dr Mowlam's initiative comes at a time when that arrangement is under extreme strain.
Last week two Ulster Unionist MPs, furious over the selective leaking of the joint British and Irish "framework" document, threatened the party would bring down the Government.
Labour believes this scenario is highly unlikely, but the speech raises the prospect of increased parliamentary co-operation between Labour and the Unionists.
During her speech, at the Royal British Legion hall in Garvagh, Dr Mowlam insisted there was no "deal" with the Unionists and reiterated party policy backing the unification of Ireland by consent, adding "consent being crucial". She set out further safeguards, including "Labour's firm commitment that the three-way guarantee will be honoured. Any balanced settlement will require the wide agreement of the political parties in Northern Ireland, the consent of the people of Northern Ireland and the consentof MPs at Westminster".
One Labour source said: "We do not believe that they will bring down the Government over the peace process, and would not support that anyway. If they chose to do so on another issue we would welcome it. But it does not take a large brain to work out that that would lead to a large Labour majority - and is therefore unlikely.''
More likely is a guerrilla campaign of parliamentary opposition. Labour sources point out that the Unionists voted against the Government over the doubling of VAT on domestic fuel, and helped to block Post Office privatisation.
The joint framework document being prepared by the British and Irish Governments is more than 95 per cent completed and Irish sources hope it will be signed this month.
Ministers may need two further meetings rather than being able to agree to a text on 14 February, when Sir Patrick Mayhew, Secretary of State for Northern Ireland, and Dick Spring, the Irish Foreign Minister, are due to meet in Dublin.
Alan Watkins, page 21
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