Sir Alex Ferguson’s amazing love letter reveals the depth of passion he felt for Manchester United star Eric Cantona

There is a vivid sense of him casting wistful glances, hoping to see the Cantona car

A few more scores are settled and there are some more illustrations of the power plays that went on behind Old Trafford’s closed doors. But then, almost an after-thought, is the short letter – the most extraordinary letter – which in 600 words or so reveals more than all the collective wisdom the Harvard intellectuals have distilled and put down on paper in Leading, their new book about Sir Alex Ferguson.

It is tucked away (in full here) amid the book’s images of miscellaneous correspondence, entitled “The Archive”, and is nothing less than a love letter, written on 18 August 1997, by Ferguson to Eric Cantona when the player had decided to leave Old Trafford. We always knew that he considered him special. Yet, to read Ferguson telling Cantona about the summer days, before the 1997/98 season, when he hoped in the face of all reason that they would spend another campaign together, is to appreciate that there was a kind of a mourning for the manager after he had told him he would be gone.

“When we re-started training, I kept waiting for you to turn up as normal but I think that was in hope not realism and I knew in your eyes when we met, your time at Manchester United was over...” Ferguson writes, the sense so vivid of him casting wistful glances to the Carrington gatehouse, hoping he might see the Cantona car. His life is going on much the same as he writes. Cantona’s is on another plane, destined for screen and stage. But the older one left behind looks for a way they might yet still connect. “One thing, I would like you to remember is to remain active and fit,” Ferguson says, reaching back 33 years to locate some common experience. “I always remember when I finished at 32 and I started management, I was more concerned about organising training...”

He confides in Cantona that the man he’s just signed to replace him, Teddy Sheringham, is struggling. “He is finding it difficult to find the space he got at Tottenham and is playing deep so we have some adjusting to do. Players sometimes don’t realise how difficult it is to play at our level…” In that “our” is the message that they share an appreciation of the challenge which others – Sheringham – cannot know. “I just hope he can do it for us,” Ferguson reflects.

It is resonant, reading the letter back, that he shifts directly from Sheringham – who would become his European Cup winner within two years – to the agonies he felt at not having won that very prize. “I have not won the European Cup and it does get to me at times,” he writes. He yearns for the elusive Gallic spirit again. “I keep hoping that I will discover a young Cantona! It is a dream!” And he wants to retain relevance for the spirit now gone. “You are always welcome here and if you just pop in unexpectedly for a cup of tea, no fanfare, just for a chat as friends, that would mean more to me than anything. Eric you know where I am if you need me and now that you are no longer one of my players, I hope you know you have a friend…”

The tenderness is so striking in an individual characterised as being in possession of none. But his fervent wish to maintain the link – and the reason why he indulged Cantona at times – belong to one of the characteristics which made Ferguson great. It is his fascination with new ideas and territories. A desire to broaden his mind. His signing of Cantona from Leeds United has always been characterised as an impulse – “Ask him about Eric,” he scribbled on chairman Martin Edwards’ writing pad when Bill Fotherby, the Leeds chief executive, rang, asking to buy Denis Irwin. But Ferguson had already sought professional opinions about Cantona. Several people, including Gérard Houllier, had told him he had broader interests, an intellectual faculty and would be a challenge because of that.

Ferguson has always been fascinated with new worlds and those who might help him find them. Gary Neville always said as much. He described in his own autobiography Ferguson’s absorption with the marginal gains medical science could bring – podiatrists and ocular scientists. So much of the other stuff – the fascination with wine, languages, piano-playing, France, New York – belong to that same search for new worlds. The Frenchman, 25 years his junior, delivered them, just as Houllier had promised.

There is a sense of all this in the Weekend FT interview published two days ago in which Ferguson’s collaborator on Leading, the venture capitalist Michael Moritz, describes their first meeting. It was at Metropolitan Club on New York’s Fifth Avenue, where they drank a bottle of Californian Stags’ Leap wine and sat on the balcony overlooking Central Park. “Red wine was the motif for those meetings,” Moritz says. It was Ferguson’s curiosity with the world beyond football, including the American Civil War, which impressed him.

But Cantona brought more than that to Ferguson’s door. Fragility and the need for encouragement arrived with him, too, and that is something else that Ferguson always thrived upon. The hairdryer motif crassly oversimplifies, obliterating how he wanted players to come to him with problems and help them to find a way around. There was a significance to what Ferguson said of Cantona in his compelling recent interview with my Telegraph colleague Paul Hayward, who has come to know him well. “I spoke to Cantona every day,” Ferguson said. “He was a very underrated man and an interesting man. He needed the encouragement that he was at the right club.”

There would be no Cantona car at the Carrington gates, of course. Nor those cosy chats the Glaswegian hoped for, as his talisman nonpareil eased away into new realms. But the remarkable part of all this is that Ferguson, aged 55 when Cantona left, still had most of his vast accomplishments ahead of him. When Ken Loach’s film Looking for Eric, in which Cantona plays himself, reached the screens in 2009, Ferguson took his entire squad to see it at a south Manchester cinema. There is a nostalgic reprise during the credits of Cantona’s legendary lines about “the seagulls chasing the trawler” and it apparently had Ferguson in stitches.

It’s not so hard to imagine him sitting there in the darkness of the cinema, reflecting on how it might have been had the Frenchman stayed, committed for the long haul and shared in far more of the incredible glories.