As the US President, his wife and daughter headed for Britain last night the Northern Ireland Secretary, Mr Peter Mandelson, said President Clinton had provided the focus to get a resolution to the difficulties threatening the peace process.
After seeing Mr Clinton off on his flight to London, Mr Mandelson said: "I think what President Clinton did as a really big player was focus everyone on the big picture here in Northern Ireland and the fundamentals."
Mr Clinton had shown what had been achieved and how far they had come - "therefore what we would stand to lose if we allow things to roll back", he said.
Speaking at Belfast International Airport as Air Force One left the ground, he said: "It has been a good day for us in Northern Ireland because above all it's been about substance rather than style.
"We have created the basis today on which we can build in the coming days and that is what we are determined to do . . . to complete the work that President Clinton has encouraged us so much in, not just today but over the years he has been contributing to the peace process."
He welcomed the announcement of a US, British Irish combined drive against terrorists opposed to the peace process.
"That must be welcome to all those who prize and want to unite against the dissidents disrupting our efforts."
Later Air Force One touched down at Heathrow amid tight security. Mr Clinton waved to waiting reporters as he left the plane, followed by his wife Hillary and daughter Chelsea.