Leslie Southwick appeared on Coronation Street in four roles:
- A Pop Singer in May 1963
- A Policeman in August 1963
- Skinny Williams in January 1966
- Eric Briggs in February 1967.
His other credits include The Man in Room 17, Public Eye, Softly, Softly: Task Force, The Mind of Mr. J.G. Reeder, Take Three Girls, The Man Outside, Warship, Dial 'M' For Murder and Fortunes of War. On the big screen he had an uncredited role in the 1967 Hammer classic Quatermass and the Pit.