James Corden has revealed that the false teeth he wears in One Chance gave him a lisp.

The Gavin And Stacey star needed time to adapt to the clip-on set of gnashers he had to don for his portrayal of Britain’s Got Talent winner Paul Potts in the film.

“I had to work with them for about four or five weeks before we started shooting, because initially when you put those things in, you immediately have a terrible lisp and you sound like Chris Eubank,” he said.

“Then, very slowly, you get used to it and you forget you have them in. You order your lunch in the catering van, and you see some dude going, ‘He really should see a dentist at some point’. But they were fine, they just clip on at the front of your teeth.”

James said Paul approved of his performance in David Frankel’s biopic, based on Paul’s life before he won the ITV talent show.

“He’s given us double thumbs up. He was sat behind me while we were watching it at the movie premiere at the Toronto Film Festival, and he seemed to really enjoy it,” the 35-year-old said.

The stage and screen star admitted he didn’t spend a lot of time with Paul to perfect his portrayal.

“I didn’t spend a huge amount of time with him, because he was touring,” he said.

“Normally, when you’re playing someone who’s alive, it is incredibly difficult, but for me, I don’t think it was. The film stops at the moment he auditions for Britain’s Got Talent and that’s the very moment you and I became aware of him. The person I’m playing isn’t the person that we know now so it was easier.”

One Chance opens in cinemas on October 25.