The Greatest Englishman will chronicle Captain Matthew Webb's 1875 swim from Dover, England to the shores of France.
Brown says, "Being a part of this project has been a fantastic experience. Captain Webb was a brave and courageous man who made the impossible happen through sheer determination and courage and it has been an honor to bring his story to life."
Justin Hardy is directing the film and Mercury Prize nominees British Sea Power have signed on to compose the soundtrack.
The movie will be released next year (14).