Actress Samantha Barks was given the \"biggest surprise\" when impresario Cameron Mackintosh joined her on stage to hand her a role in a Hollywood film. Barks had just finished performing as Nancy in Oliver! at Manchester\'s Palace Theatre when Mackintosh appeared. He said she had been chosen to join the cast of Les Miserables, which will also star Hugh Jackman and Russell Crowe. Barks, 21, of Laxey in the Isle of Man, described it as the \"happiest moment\". She will play the role of Eponine. The former competitor in the BBC talent show I\'d Do Anything said the news was \"still sinking in\" and it was the \"biggest surprise of my life\". On stage, Mackintosh said he had searched theatres in Hollywood and on New York\'s Broadway and London\'s West End to find the right actress. The impresario, who previously cast Barks in the role in a theatre production of the musical, said the film\'s director, Tom Hooper, had chosen her to reprise it on the big screen. It had previously been reported that singer Taylor Swift would play the tragic Eponine, one of the central characters in the story, set in 19th Century France and originally a novel by Victor Hugo. The Les Miserables film is due to be released in December and will also feature actresses Anne Hathaway and Amanda Seyfried, who previously appeared in the screen version of the hit musical Mamma Mia! Mackintosh said it was \"so rare\" for a recently unknown performer to make such a quick rise \"in our business\". \"This is a real rags-to-riches story - a 17-year-old who had done nothing when she started out on I\'d Do Anything on the BBC,\" he said. In 2008, Barks reached the final of the show, which allowed the public to choose an unknown actress for the role of Nancy for a new production of Lionel Bart\'s Oliver! She finished third in the competition, behind winner Jodie Prenger, but eventually landed the role of Nancy in 2011.