Downey's back on track

He is the Hollywood star who had it all and threw it away in a spree of drink and drugs that landed him in prison.

Now Robert Downey Junior is back starring in a new hit film. And today he paid tribute to the woman who is described as his "saving grace".

The troubled actor, who spent a year in jail for possessing heroin, cocaine and a handgun, was with girlfriend Susan Levin, a film producer, at a screening of his new film, The Singing Detective.

The couple, who met on the set of the thriller Gothika, are even reported to be engaged with plans to marry next year.

The 38-year-old actor, who is tipped for an Oscar for his performance as a novelist crippled with psoriasis - a role made famous by Michael Gambon in the BBC series - has been dating Levin for seven months.

He told the Standard they were thinking of buying a property together in the UK. "I think we would prefer to live on the coast, maybe Brighton," he said.

A friend of the couple said: "Susan has been his saving grace.

"She has made it clear to him that he must stay clean if he wants to keep her and that's enough of an incentive for him.

"You can really notice the difference in his behaviour since they met. He is smiling, he has lost weight and there is a real spring in his step. They have fallen head over heels for each other."

Levin was dressed in a black dress with a plunging neckline for the screening at the Everyman Theatre in Hampstead.

Trudi Styler, who is working with Downey on a new film called A Guide To Recognising Your Saints, described him as "very edible".