Writing in his updated autobiography, Ferguson described Van Gaal as “a good choice”.

He said: “Louis, who took the job, is what I would call a managers’ coach. He’s one of these committed ultra-professionals. Football is his life.

“Wherever he has managed, every footballer will have learned from him. He’s strong, single-minded, as he showed again with the Netherlands at the World Cup - a marvellously entertaining tournament which supported my earlier point about teams counter-attacking nowadays en masse.

“I like Louis and have always had a good rapport with him. If I had to choose one word for him it would be ’formidable’.

“His urge is to play attractive football. He likes to watch players play and players train and to be involved at all levels, including in the development of young players.

“His background at Ajax shows that his faith in youth will not diminish. He was a good choice.”

Ferguson also applauded Van Gaal's decision to appoint former midfielder Ryan Giggs, who took over from Moyes on a caretaker basis, as his assistant.

Predicting that the Welshman would thrive under the older man’s influence, he said: “Louis could help Giggs learn about this business. In turn, Ryan could help Louis in understanding the inner workings of United.

“As I look back on all those trophies, and those 963 appearances and 168 goals, I recall him as a physical freak. How he could have performed at the level he played at for all those years is beyond me.

“With Giggs I found perfection.”

The additions to Ferguson's story also include his reflections on a series of opposing managers, with an old foe - Arsenal's Arsene Wenger - among them.

Wenger’s Gunners ended a long wait for a trophy with a 3-2 FA Cup final victory over Hull in May, and while that meant disappointment for one of the Scot’s acolytes, Steve Bruce, he did not begrudge the Frenchman his success, and admitted he could come close to beating his 26 years in the same job.

Ferguson said: “Arsene has always been dogged and determined about his beliefs and has never succumbed to pressure to change.

“The standard and the method have been consistent. He has always been good at acquiring and developing young players. He is never afraid to play young people - which is bold, because young players are not fully formed.

“Who is to say that Arsene will not beat my record? I have my doubts, but he’s having a good crack at it.”

If Ferguson was a spectator for the 2013-14 season, he remained very much involved and revealed he had conversations with Tony Pulis before he accepted the Crystal Palace job and Barclays Premier League-bound Burnley boss Sean Dyche on several occasions.

He voiced his support too for old ally Sam Allardyce, whose style of football was called into question by West Ham supporters last season.

Ferguson said: “I hope that before I die, someone can explain the ’West Ham way’. What is it? They last won a trophy in 1980, the FA Cup.

“I never played against any West Ham team that played football I was afraid of. They were always surviving, or lucky as hell against us.

“I had to sympathise with Sam. He couldn’t win. There is this preconception with West Ham fans that Big Sam is a survivalist who tells teams to boot the ball up the pitch.

“The truth is that he stayed up with a team of very average players. That’s management. He drew the best from them.”