This is an extract from the authorised biography of Sean Fallon, by Stephen Sullivan:

IT was midway through the second half of a tempestuous 2-2 draw with Bari on Celtic's 1970 end-of-season tour of North America. Jock Stein turned to his assistant, Sean Fallon, and said simply: "I'm away home."

Within seconds, he had disappeared up the tunnel and was heading for the airport. Fallon was stunned. Celtic still had four matches of the tour to negotiate and he was left with players, staff and journalists pressing him for answers that, having been deserted without warning, he did not have. Eventually, Stein released a statement claiming that he had returned to handle a backlog of paperwork and receive treatment on his troublesome ankle. The truth, his wife Jean later revealed, was that "he didn't have his heart in it".

There was an additional factor. Celtic's first opponents on that tour had been Manchester United and it was while in Canada for that fixture that Jock Stein began tentative discussions about moving to Old Trafford. It was the beginning of a saga that would take most of the season to resolve and, for once, the manager chose to keep his principal confidant largely in the dark.

"Jock was very cagey about the whole thing," said Fallon. "He told me later that he was thinking about moving, but I think he knew I was annoyed with him over upping and leaving like that in America. That was one time I wasn't entirely happy with Jock. The uncertainty about the Man United thing wasn't helpful to anyone and I felt he could have been more up front about it all. But you just get on with it. There wasn't a big fall-out or anything like that; I just let him know what I thought. I wanted it sorted out one way or the other."

For weeks, months even, it seemed likely that Stein would leave. By February 1971, patience was wearing thin, with the minutes of a crisis board meeting revealing a hardening of attitudes towards the club's vacillating manager. "It was agreed to put out to the manager that he was being paid a very high salary, that 'loyalty to the club should play a very important part' in his thinking and that 'we were not prepared to enter into an auction'," the minutes read. Billy McNeill, in Hail Cesar, remembered driving to Stein's house to confront him on the persistent, unsettling rumours. "Jock was up front with me," wrote McNeill. "'I've been offered the Manchester United job, Billy, and I think I'm going to take it', he said."

Matt Busby, having made his initial approaches through Pat Crerand, met the Celtic manager at a motorway service station near Haydock on April 14, 1971. Terms were discussed and, seemingly, agreed. But within 48 hours, the deal was off. As Crerand explained: "Later that week, Matt said to me: 'That's some pal you've got. He took the job and then phoned me this morning to say he's not taking it after all.' I was surprised because I knew Jock definitely fancied coming to United, although I knew Jean [Stein's wife] didn't want to leave Glasgow.

"It was a shame because Jock would have been ideal for United at that time. To have had him and Sean come down, it would have been the perfect set-up. There's no doubt that he'd have brought Sean along, and I would imagine Neilly Mochan would have come, too."

Plenty would have made the same assumption, although George Stein suggested that this was in fact a critical issue on which Busby and his father did not see eye-to-eye. "Initially I was sure that he was ready to accept," he said in Jock Stein, the Authorised Biography. "Gradually, though, the more he talked, the more the doubts filtered through. Not about my mum's feelings, because he knew that she was reluctant to move, but about the job itself . . . He was insisting that he wanted to bring in his own backroom staff so that he had his own people round about him. But Sir Matt had his own loyalties."

Yet if this is indeed the case, and Stein was fighting for Fallon's place in the Old Trafford hierarchy, it was a needless battle.

"There's no way I would have gone with him to Manchester United. Jock never spoke to me about joining him there, but it wouldn't have interested me if he did. I wouldn't have left Celtic unless they wanted me out. Why would I walk out on a club I'd always dreamt of being part of? Manchester United is a great club as everyone knows, but it's not my club. So, honestly, I wouldn't even have been tempted. Jock and I had great years together and were very close, but my main loyalty was always to Celtic and he knew that. I actually don't think he would have asked me to come with him and, if he did, he would have expected me to say no."

As it happened, Fallon and Stein were at Old Trafford the following year, though merely to provide the opposition for Bobby Charlton's testimonial. But as Celtic's players trotted out for their warm-up, disturbing news reached the club's assistant manager. An enormous box of chocolates had, he was told, just been delivered to Old Trafford for his wife, who had travelled down for the match with Jean Stein. This was disconcerting because Fallon had ordered no such gift, and realised that Myra would know that only too well.

"It turned out Sean Connery had sent them. I know - the last man you would want sending chocolates to your wife! He was a good friend of ours at that time and would often come for dinner at our house in King's Park when he was over for games. I used to pick him up at the airport and he never wanted to go to a hotel or anywhere fancy. He always preferred to come up to our house. He was a lovely man. He'd be telling Myra, 'Now, please don't be going to any bother for me'. As you can imagine, she wasn't exactly put out by him being there. That was during his James Bond days, so he was the biggest heartthrob around.

"I remember once, when we were going to Celtic Park with him in the car, we stopped by the Steins' house to pick up Jean. She didn't know that he was with us, so we got him to go to the door and shout up in that great voice of his, 'Jean, are you ready to go?' All we heard was her screaming 'Oh my God!' He was just a very down-to-earth guy who liked his football and happened to be almost as handsome as me . . .

"I nearly had a heart attack that night at Old Trafford. But I must give him his due because, although he always had a soft spot for Myra, he never tried to steal her away from me. It was just a thank you for having him up for dinner again. It said a lot about him, and he was a pal of ours for quite a few years."

* Sean Fallon: Celtic's Iron Man, the authorised biography by Stephen Sullivan, is available in hardback from all good bookshops. It is also available as an ebook