Sir Jackie Stewart has defended his long-standing friendship with Roman Polanski ahead of the controversial director’s appearance at the Cannes Film Festival this week. In an interview with The Independent, the Scottish Formula One racing champion told how he had stood by the film-maker throughout his court cases concerning his unlawful sexual intercourse with a minor.

“I don’t think you ever should turn your back on a friend,” Stewart said. “The moral side of it I don’t want to comment on. That is Roman’s own business. But I’ve always felt him as a friend and he will always be a friend.”

Stewart and Polanski – the director whose films include Rosemary’s Baby and Chinatown, will be on the red carpet at the festival on Wednesday for the premiere of Weekend of a Champion, a restored and updated version of a documentary Polanski made about Stewart’s attempt to win the Monaco Grand Prix in 1971.

The pair first met when the director was living in London in the late 1960s with his then wife, the American actress Sharon Tate. Polanski occasionally used to watch Stewart race. Stewart had dinner with Polanski and Tate the evening before Tate, too pregnant to fly, left for the US on the Queen Elizabeth II ship. A few weeks later she was murdered in Los Angeles by members of the Charles Manson gang.

Stewart said stars from the world of entertainment and racing went well together: “When you’re at the very top of your game, whether you’re an entertainer or a sportsperson, somehow it is different from being a businessman,” he said.

“There’s an allure about it ... The very good people are very nice to share time with. I admire Roman’s skills. When you meet someone who’s awfully good at what they do and you’re doing something they admire, I think you share an affinity in stretching for excellence – taking that extra step to make something particularly good.”

Weekend of a Champion was produced by Polanski and directed by Frank Simon. However, Stewart remembers that Polanski shot most of the documentary himself. It was also Polanski who decided to revisit the film now. “He’s a brilliant man,” Stewart added. “As a film director and even producer, he is one of the greats of his time … Roman is a stimulating man. He has a fascinating mind.”

The period in which the film is set was one of the most deadly times in Formula One, with drivers such as Jim Clark, Jochen Rindt, Piers Courage and Francois Cevert dying on the track.

“The 1971 Monaco Grand Prix was in the middle of what was by far the most dangerous period in the history of Formula One,” said Stewart. “It was from 1968 till 1973 which happened to be my top, halcyon years. In those days, if you raced for five years, there was a two out of three chance you were going to die – a one out of three that you were going to live.”

Stewart speculates that it was partly the high stakes that made the sport so fascinating and exciting to outsiders like Polanski. “The drivers today are every bit as good as any driver of the past. Fernando Alonso is as good as I ever was, or Niki Lauda was, or Jim Clark was, or Stirling Moss, or Fangio oranybody else. The animal is the same type of person.”