After Paddy Crerand signed for Manchester United from Celtic on the fifth anniversary of the Munich Air Disaster in 1963, he quickly recognised two things about his new club.

Firstly, the tragedy had cast a shadow over United that would never, ever go away. Secondly, no-one spoke about it.

'Nobody ever mentioned the crash in all the time I was at Manchester United,' says Crerand, who spent eight years at Old Trafford. 'Everybody knew about it but nobody ever spoke about it. It was too hurtful for them.

Paddy Crerand has opened up about the Munich Air Disaster's impact on Manchester United

He signed for United from Celtic on the fifth anniversary of the Munich Air Disaster in 1963

Crerand has opened up about that and then-manager Sir Matt Busby in the new 'Busby' movie

'Most of the people at United when I went to the club had been there prior to the crash. They knew all the players so it would have been an incredible blow to them.'

That included, of course, the manager Matt Busby.

Busby had fought the Football League to make United the first English club to play in the European Cup after winning the title in 1957.

He felt a terrible responsibility for the deaths of eight of his young players and three members of staff when United's flight crashed on the runway at Munich on February 6 1958, killing a total of 23 people.

British European Airways Flight 609 was making its third attempt to take off after stopping to refuel en route from Belgrade where United had beaten Red Star on aggregate to reach the semi-finals. It was the last time the Busby Babes played together.

A film about Manchester United iconic manager Sir Matt Busby was released on Monday

The film chronicles the career of Busby at United during 25 years of heartbreak and success

'Matt blamed himself for the crash,' says Crerand. 'Don't forget, he had that team as kids. He was like a father to most of them more than anything. Matt took a lot of responsibility because of the European thing.

'It was Matt's dream. He thought the European Cup was going to be the biggest thing outside the World Cup. The idiots who were running football, in England in particular, didn't want to participate. There were small-minded people in football in those days who couldn't see further than their nose. Matt was way ahead of his time.

'I think one of the rules then was that you had to have your team back in the country 48 hours before you played a league match and the pressure of getting back didn't help. That plane should never have left the runway. That would never have happened today, it would never have taken off.'

Inevitably, Munich is a central theme in the new film Busby, a poignant feature documentary that premieres in cinemas on Monday evening.

From the producers of Class of '92, it tells the story of how United's legendary Scottish manager led the club from the wreckage of Munich to European glory a decade later, creating a legacy that lasts to this day.

The Scot's greatest triumph came in 1968 when he guided the Red Devils to the European Cup

It came 10 years after Busby nearly lost his life during the tragic Munich Air Disaster of 1958

The wreckage of the plane that crashed while trying to take off in snowy conditions at Munich

The United team had stopped at Munich to refuel on their journey back from Belgrade

A mural showing a photograph of the United team prior to their European Cup match with Red Star Belgrade in 1958 on the facade of Old Trafford

United's famous team of Busby Babes were decimated by the crash. They were (from left, standing): Eddie Colman (killed in the crash) , Billy Foulkes, Ray Wood, Roger Byrne (killed), Mark Jones (killed), Duncan Edwards (killed); (from left, kneeling) Dennis Viollet, Johnny Berry, Tommy Taylor (killed), Billy Whelan (killed) and David Pegg (killed)

The tragedy almost took Busby's life as well. He spent more than two months in hospital recovering from his injuries while his assistant Jimmy Murphy took charge of team affairs. It's possible that Busby wouldn't have returned to work had his wife Jean not insisted that he did to honour the boys who never came home.

He set about rebuilding his United team, bringing in key players like Crerand and Denis Law. Both men appear in the film. When United beat Benfica at Wembley in 1968, Crerand agrees that it closed the circle on Busby's pursuit of the European Cup.

The memory of the those who died at Munich lives on, though. The film is being released just a few weeks after United played in Belgrade and laid a wreath at the Partizan Stadium where the Busby Babes faced Red Star.

Former Manchester United players Mickey Thomas (left) and Bryan Robson carry a wreath onto the pitch at the Stadion FK Partizan to honour the victims of the 1958 Munich Air Disaster

'The whole of Europe knew about Manchester United because of the youth of the team,' says Crerand. 'I think that affected people more than anything. They knew how young the players were who were killed and what their lives would have been.

'The whole of Britain and Ireland went into mourning. It was unheard of for a team as young as that to be successful.

'It's even worse if you saw that team play and realised the possibilities and success they could have had in life with the quality of the players.

'How many times would Manchester United have won the league if that team stayed together for another 10 years? They would have won the European Cup, of course.

'That is never going away, Munich. It's still there today. It will be in the history of Manchester United and talked about long after we're all gone.'

Busby is in select cinemas from November 11. Own it on digital November 15, and DVD & Blu-ray November 18.