Of it all, of all the names, the games, the places and faces, the successes and failures, the good, the bad and the ugly, the characters, from street to shipyard to stadium, from Belfast to Barcelona, the Communists, the jailbirds, the drinkers and the fighters, of it all, in the midst of the quarter of a million words that went into the construction of Alex Ferguson's Dickensian labyrinth of an autobiography, there stands out one sentence that encapsulates the essence of Ferguson's life and career. It comes on page 163, during a section on his early time as a manager of struggling, unfashionable Aberdeen. Ferguson, explaining his developing managerial philosophy, states: "I wanted the team to declare themselves through creative aggression."

On re-hearing the line as he sat back in consideration in the relative tranquillity of his humdrum office at Manchester United's training-ground, Ferguson acknowledged its personal significance and greeted its reappearance like it was an old friend. Two decades on from those Pittodrie days the perception that Ferguson himself has been declared through creative aggression is one with which he is most comfortable. "Yeah," he said with a smile. "That sums me up."

And on this December day, British football's creative aggressor supreme had quite a lot to smile about. He had in fact three reasons to be cheerful that particular week. First, United had finally recognised via their pay structure the fundamental importance of Roy Keane to the club. Shortly after that Keane scored the opening goal of a potentially fraught but ultimately straight-forward encounter with Valencia in the Champions' League. And then on the Saturday afternoon, with United resting controversially, Ferguson had gone to the Racecourse Ground, Wrexham to see his son Darren score the goal that put Middlesbrough out of the FA Cup. Life's not bad for Ferguson and co.

The family pride he will have derived from the third of those events probably eclipsed the professional pride to be taken from the other two, although as he sat in icy Wrexham the embarrassed thought that he should not be there was almost certainly present in Ferguson's mind as well.

This morning, as he and his players finish their 12-hour flight to Brazil to contest the inaugural World Club Championship, such thoughts may occur again, because the stress caused by Manchester United being absent from the world's oldest competition will not be eased until they return to the third round draw next season. Ferguson knows it, the United players know it. "I am a traditionalist by instinct," he said defensively. "We didn't want to go to Brazil, that's the nuts and bolts of it. The circumstances changed that." However, now that what Ferguson described as "all the carry on" is finished, United are bound for Brazil and, as he said before the equally derided Intercontinental Cup in Tokyo: "when these situations present themselves, at Manchester United it is the culture of the club to try and win." It is Alex Ferguson's culture, the culture of creative aggression.

And Manchester United did win that game in Tokyo. Beyond Manchester 16, beating the Brazilians of Palmeiras, whom they will not be meeting in Rio de Janeiro, may not have been regarded as glorious an occasion as those victorious nights earlier in the year, but within United, perhaps very surprisingly, the most important of the club's 1,670 employees (an astonishing figure comprising many part-time employees who work only on match days) thought it "brilliant". Only now, though, has Ferguson revealed why - the Tokyo trip may well have persuaded Roy Keane to remain at Old Trafford.

Otherwise yet another physically arduous trans-continental experience would have been a journey too far mentally and literally for a man for whom New Year's Eve brought a 59th birthday. "Apprehensive," was Ferguson's description of how he felt before "going all the way to Japan."

But, having never envisaged it being so rewarding, Ferguson was delighted to be able to say "Tokyo would have helped" when discussing his captain's hesitancy about signing a new contract. "The players were brilliant in Tokyo and the atmosphere in the dressing-room afterwards was brilliant. So I think Roy saw that the players still wanted to win. It was actually a brilliant exercise." The lengths to which some people go.

Elaborating on the Keane contract, Ferguson then said of the economics: "the figures didn't come into it at the end of the day. There were two points: one, yes Roy got treated financially correctly because he's been offered more by other clubs. The second thing was in his mind - `are we still a big club?' " It is a question the manager may have been asking too. Both Ferguson and Keane found an answer in the east.

The collective sigh of relief in Manchester was tangible - the European champions are not on the verge of a premature dismantling. But did Ferguson share the view that a Keane exit would have been the beginning of the end of this team?

"Over the years I've lost some great players," he began his reply, "Robson, Bruce, Hughes, Pallister, the nucleus of that great side of '94. Then when Cantona left it was a blow to us because he was such a charismatic figure, plus a talisman. The first year after Eric we struggled, we never won anything. The next year we won the double but we knew Peter Schmeichel was going to leave from the October and with the Roy Keane situation there comes a time when you have to say enough is enough, you just can't afford to lose someone like Roy Keane. Peter Schmeichel was an influential figure and he and Keane were driving forces at the club. One goes, you don't want to lose two. If Keane goes, I think all the major influences would have gone with him."

It seems reasonable to take that as a yes.

So no wonder there has been tension discernible within United over Keane. Was it, as has been suggested, a resignation matter for Ferguson? "That's not my job. My job is to regenerate, if I can. That's what I would have had to have done. That wouldn't have been a resignation question, it might have been other matters."

Disappointingly, at that intriguing point, for the umpteenth time that morning, the telephone on Ferguson's messy desk rang loudly. Nor for the first time that day was the voice on the line that of Aidan O'Brien, ringing in with bulletins from the gallops. The news seemed to be good. "Done well," says Ferguson and, when the receiver goes down, "great man." Ferguson has many Irishmen on his mind today, not just the Roy boy.

Because if Ireland and Manchester United go back a long way, so do Ireland and Alex Ferguson. He is tracing his family roots and thinks the original Fergusons moved to Scotland from Ireland "around 1780". "Ferguson is a Gaelic name and we all think my grandmother was Newry-born," he said. "We're trying to trace that out."

More recently, in the 1930s, the family Ferguson decamped to the Newtownards Road in east Belfast to search for work in Harland and Wolff and for sport with Glentoran. Alex Ferguson snr found both and played at the Oval alongside the legendary Peter Doherty. "My dad said Peter Doherty was the best player he ever saw. Funnily enough, so did Bill Shankly."

Ferguson snr also found sectarianism in Belfast, something that would scar his son's playing days at Rangers. Like his father, the Protestant Ferguson married a Catholic. At 1960s Ibrox it would have been easier for Ferguson to be openly homosexual. He was banished to the reserves, then sold to Falkirk.