More than 100 people camped overnight at the Tesco Extra store in Stretford, Manchester, to see the former Manchester United boss - some of whom had earlier attended Wednesday's Champions League win over Real Sociedad.
By 8am in the morning about 1000 fans had gathered and were given wristbands to hold their place in the queue as the crowds increased. Tesco book buyer Hazel Powell said: "It is the biggest crowd we've ever had for a book signing."
The event was the sole UK signing of Sir Alex's second autobiography.
Mark Wood, 34, from Audenshaw, Tameside, had arrived at 7am and finally got his book signed at 2pm. A season ticket holder in the East Stand at Old Trafford, he said: "It was worth every minute of the wait. We had a nice little chat. I said to him, 'You've been told a thousand times, but thanks for everything you have done'. He said, 'It's a pleasure'.
"Kids have only ever known him and for the older generation he's been the boss for the majority of their lives. He's touched a lot of people's lives."