Gary Neville in The Daily Mail:

It was a Saturday morning game for the youth team at the old Cliff training ground. I was lucky. I was in a side that had Paul Scholes, David Beckham and Nicky Butt, who had scored a hat-trick, and at half-time we were 3-0 up against Chester.

We were all 16 or 17 so we must have felt pretty pleased with ourselves. That was until we got to the dressing room. Sir Alex Ferguson was there. The room went quiet. It was not a surprise for him to come to watch, but on this occasion he had decided he wanted to take the half-time team talk. And he set about us.

There was something he had seen, maybe a slackness or an over-confidence, that he wanted to address. And he let us know about it. We would have been terrified even if he had not been the manager. He had an aura, as did his assistant, Archie Knox. You would hear those deep Scottish accents and they would walk into a room and everything would go quiet immediately.

It has been a momentous week with Sir Alex announcing his intention to retire at the end of the season, and though we all knew it had to come, it is still hard to process. It is impossible to identify exactly what has made him unique in football, such a gigantic force. There are many complex reasons why he is as successful as he is.

But a few memories do come back from the years I spent playing under him that perhaps provide some clues. and that team talk at the Cliff is one. It tells you so much about Sir Alex; about his work ethic for one thing. Both he and his assistants would work every single minute God sent with every single footballer at that club. It was not just youth team games he would come to watch. When we were 14-years-old he would even come down to watch us train as schoolboys on a Thursday night.

Back then we trained in a gym – the coldest gym I have known, more like a freezer – and sometimes Archie would take the session. You wouldn’t ever hear of it now, the manager coming to watch kids training and his assistant coaching them. Archie would stand in the hall and you would pass the ball at him with a sidefoot. And he would say: ‘Take that ball back, son! Drive that pass.’ It also demonstrates Sir Alex’s passion for developing the talent of young people, the fact that he has always seen it as a duty to bring through home-grown players.

And then there is his attitude, his absolute determination to reach the highest standards. Even though we were 3-0 up, he had seen something in that game that he wanted to correct and it mattered deeply to him. He wanted to mould us into what he wanted in terms of attitude, spirit, flair, skill, mentality and being a winner. And, yes, there was an element of fear about his presence, though people who think that he ruled by fear or was constantly intimidating people do not know him.

But in those days, when we were kids, there was fear. Or you could call it respect for someone who was in charge of our football destinies, appropriate deference to an elder. Because fear hampers you but he never inhibited us, never bullied us. He was teaching us to be better. And we believed in him and would have hung on every word he said.

Later, as a group of us progressed to the first team, he would keep teaching us about what it meant to be a team. He was always impressing on us that we should look after our own. It was the upbringing he had in Glasgow, that sense that you all work bloody hard together but that you stick together through that.

So I can remember a couple of occasions when individual players had got into trouble and he was angrier with the team rather than the individuals concerned. His reasoning was: ‘why did you let your team-mate get into trouble? Why weren’t you there to protect him? You’re all responsible for not looking after him. You make sure he doesn’t get into trouble.’

He very rarely fines footballers because he does not believe in it as a means of discipline. But often when he did, it would be the whole squad who were fined because he believed we had failed to meet those standards of collective responsibility. On one occasion when Roy Keane had been wrongly arrested – he was subsequently freed after a night in the cells and no charges were ever brought – the manager was furious and tore into us.

‘Why didn’t you ring me?’ he said. ‘Why didn’t you tell me this was happening? You’ve all gone home and got into your beds and left one of your team-mates on his own! Why didn’t any of you think to tell me?’

A few years later, when I was captain and a similar incident had taken place, I questioned him in a team meeting as to whether he should fine the whole squad. It was a situation where I thought the senior players, including myself, should bear the responsibility rather than the younger ones. He pulled me aside afterwards and said: ‘Never question me again in front of the players.’ His belief was that if one falls, we all suffer. He wanted to instil that into his players, to drive into them the sense of solidarity he so values.

But the idea he is somebody who is continually abrasive is absolutely incorrect. He is a very relaxed individual, somebody who until a few years ago would join in warm-up drills, where two players try to get the ball back from eight players who are passing it around.

He could talk to his players on all manner of different subjects, far beyond football, and the myth he is someone always looking for confrontation is absolutely wrong. Training had to be hard, it had to be 100 per cent. But it was a relaxed environment, with fun and enjoyment because for him it was important the players were not inhibited. Everything was about expressing yourself and taking risks.

He has never been a conservative coach. His mantra is that you had to take risks to win football matches. He wants his players to have freedom to take players on and beat people and believe wholeheartedly in the Manchester United way.

Manchester United cannot play a 4-5-1, deep in their own box, getting behind the ball. Manchester United have to attack. He embraced that. He would never turn around and say: ‘You’re 1-0 up so now shut up shop.’ He was always giving out positive messages. ‘Go and get a second goal and kill the game.’ And when you had the second goal it was: ‘Think about the goal difference. Get that third goal.’

When you try to identify Sir Alex’s greatest achievements it becomes an impossible task. As soon as you decide on one, you come up with another that surpasses it.

Some have spoken this week about his ability to keep building winning teams in the last decade in the face of new challenges from Chelsea and then Manchester City. As a United fan, winning that first Premier League title in 1993 to remove that burden from the club, the team and the fans, would have to rank as his greatest accomplishment.

You cannot call yourself one of the best clubs in the world if you can’t win the championship in your country for 26 years. He had made Manchester United great again. The floodgates opened from there. It re-energised the club and the way players and fans felt about themselves.

But from my player’s perspective, winning the Treble, an unprecedented achievement, with seven players who had come through the youth ranks as the core of the squad, was his moment of personal utopia. That is when you sense he must have felt: ‘That’s why I was in that gym on a Thursday night watching a 15-year-old David Beckham and Paul Scholes passing a football. Because I knew 10 years later they’d be lifting the European Cup. That’s what I came down from Aberdeen to do.’