Published Monday, 07 February 2011
Mr Campbell was at Queen's University on Monday to speak about the second volume of his diaries, Power and the People - 1997-99, which chronicle the first two years of Blair's premiership.
The former Director of communications and strategy has described the Northern Ireland peace process as "one of the most compelling of all the events and issues" he was involved in during his time at Downing Street.
He says Trimble was "a hugely important part of the creation" of the peace process despite his doubts and worries.
"I think the impression on David Trimble is actually unfair", Mr Campbell told UTV's Political Editor Ken Reid.
"You sensed the division around him whenever he came into a meeting - usually because he would have the people who were about to cause the division in the room with him and that was a very difficult position in which to negotiate."
"To his great credit, he went for it because he could see that there was there a framework that would lead to a more peaceful future."
In his diaries, Mr Campbell recalls the moment Blair decided to make the peace process a priority, the first visit of the Sinn Féin leadership to Downing Street, the negotiations that led to the 1998 Good Friday Agreement, and the Omagh bombing.
Asked if he trusted Gerry Adams and Martin McGuinness during the negotiations, he replied: "Yeah, ultimately."
"The thing came from the top. Tony Blair made the judgment based on his assessment of them, of the situation, of human nature - he made the judgment they decided to try a different course. He thought they were sincere in that. You had to trust that."