Lord Fitt, who as Mr Gerry Fitt was a founder member of the SDLP and closely involved with the last power-sharing executive in Northern Ireland in 1974, watched the Assembly proceedings in Stormont yesterday.
"It has taken 25 years and nearly 3,000 deaths to bring us here today," he said.
Lord Fitt said he believed the Labour government in 1974 did not know how to deal with the new concept of power-sharing.
"Now it is different. The British government, the Irish Government, the American government - they're in support of this. In 1974, we were on our own.
"I don't think anything can stop this working now. When that Executive is set up and people go in there, they will talk about all the different things affecting the people of Northern Ireland and they will build up a camaraderie and a friendship."
Lord Fitt said this camaraderie would be enhanced by the fact that Executive members and others would have to make hard decisions on their own.
Until now politicians in the North had been able to shout at the Northern Ireland Office or send deputations over to Britain and blame them. "This time they will have to take responsibility themselves."