The Celtic chairman revealed last night that Jansen would have been ditched by the newly crowned Scottish champions if he had not decided to quit, just 48 hours after guiding the club to a first title in 10 years.
Jansen's way of working angered McCann enough to raise no protest when the taciturn Dutchman informed the club yesterday from Portugal, where he has taken the Celtic team for a friendly with Sporting Lisbon, that he wanted to use the special escape clause in his three-year contract.
McCann claimed last night that Jansen had no long-term ambition to work at Celtic and accused him of "short-termism". In outlining the flaws of the man who played in two World Cup Finals for the Netherlands, it became clear that, as far as McCann was concerned, the future was not orange. "It was the opinion of the board and myself that he could not have continued long-term," McCann declared last night.
Outside, a few hundred demonstrators chanted: "Fergus, Fergus, what's the score?" They demanded to know why the club had taken the astonishing action to part with a man who had just guided them to the trophy they had waited so long for, and, at a stroke, ended Rangers' monopoly of the league.
On Saturday, Parkhead had been teeming with 50,000 jubilant fans paying homage to Jansen and his players for delivering the holy grail. But McCann is not a football man - and that owes a great deal to the parting of the ways with the maverick Dutchman, who refused to toe the line that McCann set out. That was also the scenario with Lou Macari and Tommy Burns, both sacked by McCann who took over as chairman when he saved the club from bankruptcy in 1994.
But Celtic, as with other clubs, outlined themselves that finance matters more than football by informing the stock exchange in London first of the change which would have an effect on the club's shares.
"There is a way of working within this organisation and Wim Jansen had his own policies," McCann said. "You cannot operate like that."
McCann was particularly critical of Jansen, whom he hired a year ago after sacking Burns on the basis of the Dutchman's glowing references from, among others, Johann Cruyff, with regard to the transfer of Harald Brattbakk, whose goal against St Johnstone on Saturday sealed the title.
McCann claimed Jansen flouted club policy that all major signings be watched in person by the head coach. "We even provided a private plane, which had been hired at great expense, for him to go and see Harald and he refused three times to use it. We also asked Jansen to give a list of possible players in March that he was interested in signing, and he refused to do that. That indicated to us that he didn't intend to stay here too long."
Jansen has hinted he was unhappy about being curtailed in spending, although he used pounds 12.4m to acquire new players which brought Celtic ultimate success. However, the CV of a man who has never stayed longer than two years in any coaching job backs up McCann's assessment that clearly Celtic were going to have to look for a new coach sooner rather than later.
Jansen said from Lisbon that his decision was about "principles" and not about money, and that he has not been contacted by another club.