After a wayward past behind him, Leslie joined the navy training ship for two years. His first taste of acting came during ten years subsequent service in the Fleet Air Arm of the Royal Navy. He's been acting since the 1960s firstly appearing in minor roles in programmes such as Dixon of Dock Green, Manhunt, The Fight Against Slavery and Z Cars. In 1977 he appeared in the Doctor Who television story The Face of Evil as Calib.
In 1992 he landed the role of Philip Brookes in Coronation Street, the brother-in-law of Ted Sullivan and appeared intermittently until 1993. After leaving the role of Jeff in 2000, Leslie went on to appear in television shows Holby City, The Last Detective, ChuckleVision and The Smoking Room.
His last known contribution to television and the acting world was in the televisions series Midsomer Murders as Amos Brown in 2006.