Elton John is now astonished that he had the stamina to carry on touring and recording while fighting crippling drink and drug problems.

The pop legend battled addictions to alcohol, cocaine, and prescription medicine for the best part of two decades before finally getting sober for good in 1990.

Elton's fight with his demons is documented in the new biopic Rocketman, including how he performed at Los Angeles' Dodgers Stadium just days after almost dying from an overdose. Speaking on the blue carpet at the film's London premiere on Monday, the Tiny Dancer hitmaker said that looking back, it was miraculous what he put his body through.

"Just before the gig at Dodgers stadium I had the overdose and then two days later I was on stage. I had a lot of stamina and the show must go on," he said. "But when you look back I think. How the hell did I do it and still be working? With addiction and everything. But that's what got me through that I was still making records."

Elton, 72, is played by Welsh actor Taron Egerton in the new movie, who learned the piano for the role, and sings throughout Rocketman.

Despite the hard work, the Kingsman: The Secret Service star told Sky News playing the musical icon was a "total joy" and an "extraordinary privilege".

Revealing what Elton is like behind the scenes, the 29-year-old added: "Not only is he everything everyone knows him to be, which is a musical genius, a great philanthropist, he is the most funny, naughty, irreverent, kind, and brilliant man."

Rocketman debuts in cinemas on Wednesday.