In 1993, Brendan Duddy was quizzed for hours after then Secretary of State Sir Patrick (now Lord) Mayhew attributed a "war's over" message to Martin McGuinness.

The Belfast Telegraph understands that when questioning Mr Duddy, Mr Adams was accompanied by three other senior republicans - now Deputy First Minister Mr McGuinness, his junior minister Gerry Kelly and party Vice President Pat Doherty.

"What those people were trying to find out was how that was said - what happened," Mr Duddy told this newspaper.

He was talking about the disputed message that Sir Patrick attributed to Mr McGuinness that "the conflict is over but we need your advice on how to bring it to a close".

"From my point of view, no-one was remotely abusive to me and I felt under no threat whatsoever," Mr Duddy said of his questioning by Mr Adams.

A year ago, the Derry businessman told the Belfast Telegraph that Mr McGuinness was "psychologically not capable of asking for British advice to end the conflict".

It is a position he still holds, insisting the Deputy First Minister was " incapable of saying it".

"They (republicans) wanted dialogue with the British," Duddy said, "but not on the stupid terms that came out of the (Mayhew) message."

And, last year, he accused the former Northern Ireland Secretary of " throwing a hand grenade" into the peace process.

"It was destructive and you can make up your own mind what the intention was," Mr Duddy said at the time.

Asked yesterday what lessons he believed could be learned from the Northern Ireland conflict, Mr Duddy responded "dialogue, dialogue, dialogue" .

"The powers of government will inevitably find reasons why dialogue may not take place," the former Policing Board member said.

"The lesson coming out of Ireland is: ignore the doomsayers about dialogue, and ignore the people who take the highest moral ground to remain with clean hands and prolong conflicts that could be more speedily ended.

"Dialogue does not mean one has to surrender principles or points of view," he argued.

"It simply means making clear what is possible to talk about and what is not possible.

"It was possible to talk about ending the conflict in Northern Ireland above the needs of victory and defeat," he added.

For more than two decades Brendan Duddy was the "back channel" link between different IRA leaderships and the British Security Services - a link authorised by British Governments.