Close-Up: Adam Godley

No wonder he's worried – the actor is stepping into Dustin Hoffman's shoes

He watched on as his son was shrunk to Tom Thumb-size in Tim Burton's Charlie and the Chocolate Factory (2005), helped take down Hermann Göring in the 2006 BBC docu-drama Nuremberg: Nazis on Trial and proved a thorn in Scully's side in The X-Files: I Want to Believe (2008). But nothing has quite prepared Adam Godley for his latest role – playing the autistic-savant Raymond Babbitt in the new West End adaptation of Rain Man. Appearing opposite Hollywood heart-throb Josh Hartnett will be one thing, trying to follow the Oscar-winning performance of Dustin Hoffman in the 1988 film, will be another.

As a veteran of film and stage (he was nominated for an Olivier in 1999 for his portrayal of Kenneth Williams in Cleo, Camping, Emmanuelle and Dick and in 2002 for his performance in Mouth to Mouth), Godley remains undaunted. "Hoffman is one of my great acting heroes and it's exciting to tackle a role played by one of your idols," he says. "I try to think about it in the same way I would any other role that has been played by another actor before, and I've done plenty of those."

In preparation, he read up on autism and spoke to people who worked in the field. "I needed to look inside the head of someone with autism, which is a different place, where the world is experienced in a different way," he explains. "I wanted to store everything and then, once we started rehearsing, I tried to find what was useful to create the autistic-savant within me."

He is relishing the opportunity to play opposite Hartnett: "He's a passionate and rigorous actor and that's inspiring to be around. We're going to take the audience on a moving, fascinating journey."

'Rain Man' is at the Apollo Theatre, London W1 (0844 412 4658, www.apollo-theatre.co.uk), from Thursday to 20 December