The former manager of Manchester United, 79, admitted in his upcoming documentary Never Give In, that he had a 20 per cent chance of survival following a brain haemorrhage. He revealed he just slumped and couldn’t speak and was worried if he will be able to remember the past or ever speak again.

The documentary, which premiered at the Glasgow Film Festival on Saturday, March 6, and will be able to be seen in cinemas from May 27 and Amazon Prime on May 28, was directed by Sir Alex’s son Jason, 51.

Speaking alongside his son during a virtual Q&A after the premiere, Sir Alex said the recovery from the operation was terrifying.

He said “I lost my voice, just could not get a word out, and that was terrifying – absolutely terrifying, and everything was going through my mind: is my memory going to come back? Am I ever going to speak again?  I remember falling and so after that I don’t remember a thing. It was sudden. It stopped. It just stopped. It was no man’s land. So I remember estimating his mortality – at that point in time, it was 80 per cent. It was an 80 per cent chance he would not survive. I started to… how do I put it? I went off the rails a bit. Out on the town an all. I started going out Friday nights even, even the night before a game. My dad would say, ‘Where are you going?’, I’d say I’m going out dancing’… He said, ‘You can’t go out dancing if you’ve got a game tomorrow. Well, I said, ‘I’m on the reserves and it doesn’t mean a lot, you know, and that’s when we fell out. It got to the point when he said, ‘Go your own way! And we’ll see what happens… and then we didn’t talk to one another for two years between 1961 and 1963 – we didn’t talk. And then one night I went out and I got drunk. I ended up in jail. I went to court. I got fined £3. I was a black sheep. It’s always been in the back of my head, at that period. I’ve always regretted it. With that sort of background and upbringing I had, I surrendered.”