Seamus Mallon, the deep-green nationalist from South Armagh, is also an honest Ulsterman. A week before last month's elections to the new Assembly he was speaking his mind - lambasting unionist and republican alike.
David Trimble was being "petulant" in his attitude to Westminster legislation on early prisoner releases and would have to "reinvent himself again". Sinn Fein, on the other hand, faced a "growing imperative" to ensure "verifiable evidence" of decommissioning within the two years laid down by the Belfast Agreement.
Such honesty endears the SDLP leader to Northern Protestants. John Robb, who served with him in the Seanad, recalls a north Antrim neighbour, a strong unionist, praising the south Armagh man for "speaking his mind - you know you're getting the real thing with him. I admire his directness, even though I disagree totally with him."
The unionists' perception of John Hume could not be more different. The most brilliant Irish nationalist politician of the late 20th century tends to be seen by them as slippery and untrustworthy.
It helps that, unlike Hume, Mallon grew up with unionists in the largely Protestant small town of Markethill. His friends as he grew up were not only Protestants but Orangemen. His ease with the "other side" was clear for all to see in the body language and banter as he posed for pictures with Trimble after the two men were elected to their new ministerial posts.
He has an obvious sympathy with unionist feelings of defensiveness and isolation, as a proud but confused people who were taught for many years that they were a kind of master race and are now being forced to face the real world of equality, power-sharing and an Irish dimension.
With sympathy goes understanding, and he understands Northern Protestants better than most of his colleagues on the new Assembly's nationalist and republican benches.
"One of the ironies of the present situation - and I think it is something the Provisional IRA should look at very closely - is that the more you attack unionism in its various shapes and hues, the more they consolidate," he said in that same 1970s interview.
"The more you treat with them, the more they disintegrate; that has been the pattern. And certainly the Provisional IRA campaign - although the unionist monolith has split - is the one thing which is keeping it even partially united."
Despite - or perhaps because of - such insights, not very many years ago Seamus Mallon's reputation with unionists was as a tough, uncompromising nationalist. He made his name on his arrival in the 1973 assembly as an outspoken critic of the security forces. He was the obvious choice for deputy leader once Gerry Fitt and Paddy Devlin departed and the party moved in a more nationalist direction. His blunt, green views upset many Fine Gaelers and others in the Seanad.
The fact that he is now sitting in government in Belfast with David Trimble, a unionist of an equally trenchant tendency, is indicative of the miraculous changes that have taken place in the Northern Irish political climate in a few short years. His nationalism remains undimmed, although he says his experience in the House of Commons has taught him lessons in tactics: that "sometimes you can make a better point by understating than overstating it".
John Hume may be the SDLP's long-term strategic thinker, but Mallon is "very clever at dealing with the scenario of the moment", says one senior republican who has had dealings with him. His outspokenness about issues of the moment, notably the IRA's campaign of violence, often enraged republicans and annoyed his party leader at sensitive moments during the Hume-Adams talks.
He is invariably well briefed and on top of the subject at in hand, a strength that will endear him to the meticulous unionist leader with his academic lawyer's eye for detail.
He is an unflappable and toughtalking debater, with an ear for the telling one-liner. His taunt to Sinn Fein that when all its "verbiage" was stripped away what was being talked about was "Sunningdale for slow learners" was a defining moment in the past year's drive to accommodation.
Courage is another defining feature of the man. When asked what his chief strength is, he says "tenacity". He has needed both in a 25-year political career that has seen more depths than heights. His Markethill home has been attacked on half a dozen occasions, including one serious petrol-bombing. He and his wife have come through serious illnesses.
He was effectively out of work for many years in the late 1970s and early 1980s until Charles Haughey, a man he admired and was close to, gave him the Seanad job. He admitted in a 1984 interview that despair was a frequent visitor, but one that passed and left hardened resolution in its wake.
And he has that sine qua non of success in the Northern constitutional bear pit: an absolute obsession with what he calls the "very noble profession" of politics. He has always believed, even during the lowest times, that as a constitutional politician he was playing a vital role in two key areas - preventing the North from tipping over into total anarchy and civil war, and re-examining and redefining the deep nationalism of the Northern minority to make it constructive rather than unrealistic and aspirational.
His commitment to his profession is near legendary. Paddy O'Hanlon, the former civil rights activist who was his SDLP rival in the Newry and South Armagh area for many years, recalls looking across at him during a constituency meeting and wondering: "What do I have to do to beat that man for the nomination? I'd have to work for seven days and seven nights for many years - and I decided to go away and do law."
His moderate conservatism on social and economic issues - the conservatism of the Northern Catholic primary school principal he once was - will make it relatively easy for him to deal with unionist leaders on matters outside the constitutional arena.
"They're slightly right of centre, he's slightly left of centre - it's about the distance across a golf club floor," says someone who knows him well, recalling his early golfing prowess.
Mallon's public image is somewhat deceptive. In the past some have found his self-presentation trenchant and aggressive. One senior unionist politician who until recently knew him only from the television found that image of him "dour, sombre, even stern". When he met him he found a warm and easy-going man, full of chat about food and cars and books.
These days it is difficult to find a politician of any stripe to say a bad word about him. John Taylor calls him a "good friend who will work for the good of Northern Ireland". Rita O'Hare of Sinn Fein says he is a "tough negotiator, a formidable opponent, but always honest and honourable". John Robb says his main strength is "his absolute, complete, simplistic integrity".
"I would trust Seamus Mallon with my life. I wouldn't say that about many other politicians on my own side or the other side," said Ken Maginnis on television this week. At the age of 61, after many years as the perennial outsider, the MP from Markethill has landed, by acclaim and to many people's surprise, a key job as one of the two principal trust-builders in the new Northern Ireland.