Gwen Leitch was born in Tasmania. Thanks to a travelling scholarship she attended the Central School of Arts and Craft in London from 1954 to 1956. There she was taught by Patrick Heron and Roger Hilton. In 1956 she moved to Cornwall and lived with Delia and Patrick Heron at 'Eagles Nest', where she had a small studio space. In 1957 she was the second woman to be awarded a Porthmeor Beach Studio, which she retained until leaving the UK in 1970. She exhibited her work in Cornwall and London, and was an active member of the St Ives arts community and Penwith Art Society. She was part-time curator for the Penwith Arts Society and the Fore Street Gallery between 1959 and 1961, and also managed Bernard Leach's Craftsman Shop.

In 1959 Gwen Leitch married an English painter, Jeffrey HARRIS. Her artistic career became secondary to her role as mother and teacher. Together with her husband and children she returned to Tasmania in 1970. The following year they moved to Australia, settling in Adelaide, where she was able to resume her career, achieving considerable recognition as a painter of landscapes, seascapes and still life.

Gwen Leitch Harris died in Adelaide in 2006.