One of three children of Harry Tancred Harslett and his wife Rita, Gwenda Jeffrey describes a happy childhood in Gladstone. She went to Gladstone Primary School and then, while her father was away during the war and her mother was running the family business, she was a boarder at St Peter's Collegiate Girls' School, North Adelaide. She married Zebulon Jeffrey in 1957, and they had two sons.
Apart from a few years doing secretarial work, her whole working life has revolved around libraries. She has worked in the State Library, public libraries, College of Advanced Education library and school libraries, (both State and independent schools), including eleven years at St Dominic's Priory College. She spent three years in Administration with the Education Dept of SA as Organizer of School Libraries. She was a member, and then secretary, of the Children's Book Council in SA 1948-58. She is a registered teacher accepted by SPELD as a tutor for children with learning disabilities. She has also worked with migrants as an English tutor.
In 1988 she took a course at the Adelaide College of TAFE on writing children's stories, and in 1991 she took a TAFE editing course. As well as the writing listed here, she has published a history of the Harslett family, Hares on the Hill (1996). In the C J Dennis Literary Competition 1997 she won 1st prize in the Short Story Open Section for "The Mystery of the Glass Jar" (Not yet published). She received the Poetry Writing Award for "Oliver", Victor Harbor Folk Festival 1999, and was Commended for her story "Hiawatha's Magic" in the FAW Far North Coast Regional 12th Anniversary Competition 1999.