But while others immersed themselves in the political dark arts, the former senator gained a reputation for being a formidable diplomat, minus the ego.

Such qualities served him well when he chaired the exacting negotiations that led to the Good Friday peace agreement in Northern Ireland in 1998, and again three years later during the Middle East peace talks that laid the foundations for the proposed "road map" for peace.

Mitchell, a visiting professor at Leeds Metropolitan University, was in Yorkshire recently to give a lecture at Leeds Town Hall entitled, "Is World Peace Possible?" And while it might sound pompous, there are few people as qualified to address the question.

"If you define peace as the complete absence of conflict anywhere in the world that may not be possible," he says. "But if you define it as the avoidance of major conflicts and the effective containment of regional or local conflicts, then I believe it is possible and feasible."
There are, he concedes, some major obstacles to achieving such a peace. "Perhaps the most dangerous is the risk of the spread of nuclear weapons. There are now nine countries in the world that have nuclear weapons, many countries have the capacity to produce nuclear weapons but have voluntarily refrained from doing so.

"There's also other countries trying hard to develop nuclear weapons. If they succeed it is possible, we hope not likely,
that many of those who refrain from producing these weapons will reverse their policies. Many of the known terrorist organisations have openly avowed their attention to acquire nuclear weapons, so we could see a dramatic expansion of the nuclear powers."

But conflict, he says, is not the only barrier to stability in the world. "Climate change is a very serious threat to people all around the world, which governments and individuals have not yet dealt with effectively." Control of the world's oil supplies is another.
"In 2006, for the first time in history, oil consumption in Asia exceeded that of North America and that will continue.

"But the desire to obtain stable and secure sources of oil is influencing other major decisions, for example the Chinese government's refusal to assist in taking concrete action in Darfur is influenced by its connection with Sudan and its desire to continue having its supply of oil."

Tackling such expediency, some might say, is practically impossible, but Mitchell believes by improving fuel efficiency not just in cars, but homes and offices, we can at least begin to address the issue.

Unlike many politicians, Mitchell wasn't born with a silver spoon in his mouth. His father, the son of Irish immigrants, was raised in a Boston orphanage, while his mother emigrated to the US from Lebanon when she was 18 and worked as a janitor. Neither had a full education.

His humble upbringing in Maine had a profound effect on him, particularly his attitude towards the environment. "Where I lived there were factories along the river and back in those days it was a slum, it was where the poorest people lived because the water was so polluted. I grew up with a river that was filthy and it's an experience that doesn't leave you."

At one time, about 85 per cent of American rivers and waterways were unfit for human use, now the reverse is true thanks, in part, to the Clean Water Act that Mitchell helped to introduce. But although there has been progress he believes climate change is the biggest challenge facing mankind.

"Scientists have consistently underestimated the adverse effects, yet those who oppose taking action argue that we have to wait until there's
absolute certainty. But if you wait until there's certainty it's
too late to avoid the adverse effects.

"The truth is that individuals in their daily lives make all kinds of the most important decisions not based on certainty, but based on the weight of evidence. There are still a few doubters, but even President Bush who has long opposed any meaningful action has at least acknowledged that there's a problem."

Despite the social handicap of coming from a poor family, Mitchell shone academically. He served as an officer in the US Army Counter Intelligence Corps in Berlin, before training as a lawyer, eventually
becoming the US District Judge for Maine. In 1980, he entered the Senate as a Democrat and once in the political fray he quickly rose through the ranks.

During the Iran-Contra Affair in 1987, he famously asked Oliver North to "remember, that it is possible for an American to disagree with you on aid to the Contras and still love God, and still love this country, just as much as you do". Two years later he became Senate majority leader, a post he held until he left the Senate in 1995.

His decision to quit the Senate surprised some people but it led to his greatest political triumph. "President Clinton tried to talk me out of it and in the course of that conversation he said to me, 'if I ask you to help out would you be willing to be involved, or are you just sick of politics?' and I told him I loved politics and would be happy to help. But he didn't mention Northern Ireland, it hadn't occurred to me and I don't think it had occurred to him at that time."

However, later that year Clinton asked him to chair the peace negotiations and a week after leaving the Senate he arrived in Northern Ireland for the first time. "I thought I was only going to be there a couple of months, but I ended up chairing three separate sets of discussions over a five year period.

"While it was the most difficult thing I'd ever done it was also one of the most meaningful, it's a great place with great people and while I'm an American and proud of it, a large part of my heart will always be in Northern Ireland."

At the request of Clinton and the Israeli and Palestinian leaders he then chaired talks in the Middle East culminating in The Mitchell Report, which was subsequently incorporated into the so-called "road map" peace plan for the creation of a Palestinian state next to Israel.

Mitchell admits, though, that there is no such thing as an all-purpose blueprint for peace. "Getting people to say they will do something is hard, but getting them to actually do it is even harder. I don't
think there is any one plan you can take off the shelf and transport from one place of conflict to another, each situation requires its own solution."

However, he does believe that peace will eventually come to the Middle East. "Despite all the difficulties, about two-thirds of the public
on both sides still favour a two-state solution. It will take perseverance from the United States, because there's total mistrust between the two parties, but I believe there will be peace during our lifetime."

Although nothing is likely to happen until after the presidential elections later this year. It has been hard to escape the election fanfare, even on this side of the pond, and as one of the super-
delegates who could have a decisive say in whether Hillary Clinton or Barack Obama wins the Democratic nomination, Mitchell is well aware of what's at stake.

Although he's playing his cards close to his chest, he is confident that the Democrats will return to the White House. "I think the dismal state of the economy, the disastrous policies by the Bush administration in Iraq and mishandling the aftermath of Hurricane Katrina, will make it difficult for Senator McCain, although I certainly think he's the best choice the Republicans could have made."

At 74, Mitchell looks remarkably good but he insists he has no remaining ambitions. "I re-married when I left the Senate and I have a 10-year-old son and seven-year-old daughter, so they keep me young, or at least they keep me thinking young," he says, smiling.