What’s your daddy’s name? says the husky voice on the other end of the phone. “Mohamed Ali!” comes the little-girl response, but in the tone and lilt of a ring announcer, as if part of a never-ending show. Because Ali is not just a father to his nine children, nor even a retired and venerated fighter, but a creation, a magical illusion … and too often invisible at the other end of the telephone line.

The construct of the latest of several filmic representations of Ali’s life, I Am Ali , which opened yesterday, relies on the disembodied presence of the principal star for a couple of reasons: he no longer speaks very much at all (these are taped recordings from his voluble past) and the conversations have been rounded up by sections of his family to both celebrate his life and, not to put too fine a point on it, be part of the lucrative Ali industry.

His wife, Lonnie, is not featured but his brother, Rahman, with whom she fell out, is. So are two of his daughters, Maryum and Hana, as well as his only son, Mohamed Jr. And there is Gene Kilroy, a minor legend in his own right, Ali’s one-time business manager and confidant, who is responsible for many of the anecdotes, some hackneyed, one or two hilarious and touching.

This is not to question any of their motives. They have every right to tell their story and there are plenty of people who want to hear it. If the criteria for making a biography were to be that it be done for no financial return there would be very few produced.

And we ought not to forget a more pertinent fact: Ali loves every minute of it. He was, for those too young to remember, the standout showman of his era, certainly the funniest. He lit up not only his sport but the lives of millions with barely a passing interest in boxing, and there was not a microphone shoved towards him that did not receive the benefit of his unique wit and wisdom.

As any veteran boxing reporter would confirm, he was an interview waiting to happen. On many occasions – and this certainly does not happen today – it would be Ali who would issue the invitation to talk. It might be in a hallway or a hotel bedroom, walking along in the morning mist after the Rumble in the Jungle , or on an aeroplane packed with fight writers and an army of acolytes.

Those days are long gone and that is why we should cherish this film, which is a little way short of perfect – the timeline is all over the place, switching back and forth for no obvious reason – but which brings enough fresh material and perspective to make a valuable contribution to the chronicling of a unique, fascinating athlete.

One good reason to trust the film is the credits: it is produced by the same people who made Searching For Sugar Man , the story of the long-lost singer Rodriguez, and that was a gem. This is merely pretty good and the makers could hardly argue they did not have great material to work with.

Even in his trembling silence, living now in the clean air of Phoenix, Arizona, (Mike Tyson’s adopted home town) with his fourth wife and far away from the flash-and-pop of cameras that once recorded his every public utterance, Ali remains an eloquent force. He receives few visitors these days but generates headlines whenever rumours surface about his waning health.

What comes roaring through this excellent addition to the genre of Ali-abilia is the love for and by the man. Very few people do not love Ali and there are not many breathing souls who would escape his reciprocal emotions. He is a walking love-bomb.

“My father has a lot of sides,” says daughter Maryum. “You hear about the fights. You don’t hear about family that much or what that meant to him. He could foresee things and knew how important those things would be.”

True. But to wholly accept the image of Ali as saintly seer and dad we have to forget his serial bouts of infidelity and the rancour that accompanied all those marital bust-ups. While Lonnie did not participate here, Veronica did. “I remember the moment I fell in love with him,” she starts, “when he was … it’s going to make me cry.” And she trails off, genuinely struck dumb by the lingering power of the man. There will be rivers of tears to join those of his close family when Ali is no longer with us.

“This is a microphone,” the disembodied voice tells a young Hana, “and when you get to be a big girl I’m going to play it back so you can hear it.” And here it is.

I Am Ali is in cinemas, on Blu-Ray, DVD and Digital Download.