While attending Sylvia Young Theatre School, John got his first taste of the stage life at the age of nine, with a role in Chitty Chitty Bang Bang at the London Palladium. He was one of a group of children from his theatre school attending auditions for numerous different roles, and he was the only one to receive a part out of the group. Throughout his training, he continued to appear in theatre, racking up appearances in The King And I, and as Friedrich in The Sound Of Music.