James Corden wrote scenes for the new Paul Potts biopic 'One Chance'.

The 35-year-old actor will be seen playing the 'Britain's Got Talent' winner on the big screen, but director David Frankel admits James also penned some of the script for the movie - which captures Paul's rise to fame - and he even tried his hand at some producing.

Speaking at the premiere of 'One Chance' in Leicester Square, London, last night (17.10.13), Frankel told BANG Showbiz: ''James not only acts in the movie, he wrote scenes for the movie, he helped us produce, he helped us direct, he did everything he's really an incredible talent.

Frankel knew almost immediately that he wanted to cast the comedian - known for his role in 'Gavin and Stacey' - in Harvey Weinstein's biopic after watching him in the West End.

He explained: ''I was looking for someone great that the audience, especially in America, didn't know. Harvey Weinstein came over and saw 'One Man, Two Guvnors' in the West End, and said 'what about this guy James Corden? He is amazing. You've got to get him' So I came over.

''I was actually familiar with James' work leading up to it and of course he was brilliant in 'One Man, Two Guvnors'. He was really the only guy that we ever talked to.''