There are thousands of images of Alex Ferguson and Roy Keane winning trophies together – all conquering, smiling but far from sated; knocking not just threadbare Liverpool off their perch but all-comers and then some.

United, in their pomp, were a phenomenal force and for most of that period English football seemed to frame Ferguson and Keane as a portrait in triumph.

But few moments were as revealing as the drenched day in Cardiff in 2005 when United somehow conspired to lose the FA Cup final to Arsenal after a riveting penalty shoot-out. Patrick Viera stepped up to deliver the winning penalty strike for the Gunners, gleefully throwing salt on to what was a wounding and trophy-less season for United.

The rain fell and the camera panned around the stadium – an ecstatic Arsene Wenger in full-on Cheshire cat mode, a gloomy Paul Scholes and Wayne Rooney looking like a kid waiting at a bus stop in Croxteth – before it finally settled on Keane and Ferguson. The United manager favoured sporting fatigues that day, pale gray tracksuit darkened by rain, his hair matted. Keane, oddly enough, looked bone dry: it was possible that the rain drops didn’t dare fall on him.

In the few seconds of video tape, Keane, who had just completed his seventh FA Cup final, stands holding a sports bottle, bites his nails and says something to Ferguson, who leans in and utters what even the most limited lip reader can see is a plaintive Clydeside “heh?” And then Ferguson begins to talk, sharing his afternoon’s frustrations with the Irish man. Keane blinks and stares ahead.

It was a rare, unguarded moment that seemed to reveal much about the working and personal relationship between the two. Right then, it seemed like an ironclad alliance. It still seems hard to believe, watching that clip, that that day also marked the end. The following autumn, Manchester United started badly and Keane was gone after that incendiary row at what should have been a humdrum morning training session. Like a puff of smoke, arguably the most potent manager-player relationship in the history of English football was over.

It was hard not to recall that moment of dejection shared by Keane and Ferguson over the past few days when they showed up in Dublin, almost 10 years older if not wiser and in fine form for their separate engagements. Keane sported a professorial corduroy jacket for the official launch of his autobiography.

The best moment of the day was when Keane and co-author Roddy Doyle walked through the stadium tunnel for the photo-call. Keane slipped into playing mode, glowering as he approached the small army of lens men. But it seemed like Doyle just about managed to suppress the urge to blurt out what would have been a natural reaction: Holy f**k!

Keane may not enjoy these media extravaganzas but he is a terrific interviewee, combining forthrightness and quick temper with bursts of humour and charm. Most of the discussion was dominated by Keane’s thoughts on Ferguson’s various shortcomings. But he struck a valedictory note about his playing days, lamenting the changing culture within English football and bemoaning the “lack of characters and good lads within the game”.

Hours after the lights dimmed on Keane’s briefing, Sir Alex Ferguson took to the podium for a chamber of commerce dinner in Dublin, tuxedoed and immaculate, looking every inch the don. He must have had ’em in the palm of his hand. No more than his former player, Ferguson is masterful at playing the gallery and referred to Keane, along with Scholes, as “the best players in Europe”. Later he lamented the character of the younger players arriving at Old Trafford, describing them as “fragile” and “not like the Robsons and Keanes”. It was because “they have grown up differently”.

It sounded eerily similar to what Keane had said earlier.

Keane and Ferguson were, of course, speaking to different audiences but you always get the sense after these public orations that they are, in fact, speaking to each other in the only way their mutual pride permits. This week marked the latest exchange in a row which has been going on for almost 10 years.

Can’t some intermediary– some rock of sense and decency like Sir Bobby Charlton – step in between Keane and Ferguson and knock both heads together? They need to accept that this row is old in every sense.

There is no question but that Keane deserved a better last day at United than that swift and lonely departure

. And there can be little doubt that Keane didn’t back down an inch when Ferguson suggested that they had reached the end: it was a moment of mutual defiance. Ferguson, as manager, held all the cards.

The way in which he handled that blow-up with Keane may have reinforced his control but no matter how you spin the tale, it diminished him as a man. The fascinating question is whether either man would do anything differently if they could roll back time; if they privately wish they could have had a different outcome to their last exchange at Manchester United.

But it is irrelevant because they cannot.

Instead, that day has been relived through the slanted perspective of memoir and the saga threatens to degenerate into a schoolyard squabble. Both men have achieved too much in the game to allow this feud to tarnish the splendour of what they achieved at Manchester United.

It is funny that of all the assembled cast of United's glory years under Ferguson, the very player who seemed to enjoy the camera lights the most turned out to be the one who has conducted himself with unflinching loyalty to the values of that time. Ask David Beckham about Keane or Ferguson or anything to do with United and he will smile and pay glowing tribute while remaining loyal to the sanctity of that team, even though it has long since been disbanded. Keane and Ferguson were the soul and fury of a magnificent team and it would be a shame if they destroy the best of their life's work over the fact that both were born not knowing how to back down. It is time to either shake hands or close the door on it.