Dir: Dexter Fletcher. Starring: Taron Egerton, Richard Madden, Bryce Dallas Howard, Jamie Bell, Gemma Jones. 15 cert, 121 mins

Dexter Fletcher’s musical biopic of Elton John, a world premiere out of competition in the Cannes festival, is a rousing and emotional affair with an operatic sweep. This is a story of one of pop culture’s most extraordinary metamorphoses: Reg Dwight, the “fat kid from nowhere”, leaves his Pinner roots far behind as he blossoms forth as the flamboyant singer in the glitter and platform heels – but his success takes a huge toll.

You won’t learn here why Elton sold Luther Blissett when he was Watford FC’s chairman, but the film has plenty of other revelations and ventures into its subject’s darkest places. It was co-produced by Elton John’s company Rocket Pictures, but there is no sense that it is trying to airbrush his past.

In recent years, Taron Egerton has played roles as varied as hapless ski jumper Eddie “the Eagle” Edwards and Robin Hood. He excels here as “the introverted extrovert”, as Elton is characterised: the global superstar who, at the very peak of his fame, is insecure and miserable.

“You’ve got to kill the person you were born to be in order to become the person you want to be,” Reg is told early on. It is advice he so closely takes to heart, he risks losing his own identity altogether.

The film foregrounds the friendship between Reg and songwriter Bernie Taupin (Jamie Bell), whose part in Elton’s story isn’t always acknowledged fully. They’re portrayed as being as close as brothers. They spark each other’s creativity. Bernie writes the words. Elton puts them to music.

Almost as important is the very complicated relationship with his beloved mum (Bryce Dallas Howard). Then, there is his heady but ultimately destructive affair with his manager, John Reid (Richard Madden).

Success comes very quickly but happiness doesn’t for Elton John, played by Taron Egerton, in the biopic (Paramount)

On stage, Elton is a peerless showman. Off it, he is still the same little boy lost encountered in the first section of the film.

Rocketman begins very strikingly with a character in a strident orange jumpsuit and horns, walking in menacing fashion towards the camera. It isn’t the devil but Elton on the way to an AA meeting. “My name is Elton Hercules John and I am an alcoholic,” he confesses. The alcohol is only the start of it. “What were you like as a child,” the counsellor asks – a question that triggers the film’s flashbacks.

The low key naturalism of the Pinner scenes is in stark contrast to what follows. Elton is a shy little boy growing up in a council house in the suburbs with an aloof, jazz-loving father, Stanley (Steven Mackintosh) – who continually pushes him away and criticises him – and an unhappy mother. His doting grandmother Ivy (the beatific Gemma Jones) recognises his precocious musical skills and helps him win his scholarship to the Royal College of Music. Then he discovers Elvis, meets Bernie and realises that he has a natural flair for performance.

Fletcher (who also directed Bohemian Rhapsody) uses lavish musical sequences to whisk his way through episodes in Elton John’s life. One of the most memorable is Elton’s first performance at the Troubadour in Los Angeles – a set so full of emotion and energy that the audience takes off, and Elton himself seems to levitate above his piano.

Success comes very quickly but happiness doesn’t. The film deals frankly and without prurience with its subject’s sexual life and the misery it sometimes caused him. His attraction to John Reid is made very obvious. When Elton rings his mom from a call box outside the Albert Hall to tell her that he is gay, she inevitably responds that she has known the fact for years.

At times, Rocketman risks turning into a chronicle of woe. Much of the film focuses on the years when Elton was abusing alcohol and drugs. He was miserable in his own life and took out his unhappiness on those closest to him. This doesn’t make him very good company. His behaviour is brattish and self-indulgent. It can become tiresome to hear him say yet again how much he hates himself. However, Fletcher films even the darkest scenes in a very flamboyant fashion and manages to leaven matters with some ironic humour.