Gwladys Yvonne James was born in Wales on 23 August 1897 while her Queensland-based parents were visiting family. She was educated in Maryborough before attending the University of Queensland, where she earned a Bachelor of Science in 1918 and a Master of Science in 1920. While at UQ, she studied biology under Thomas Harvey Johnston. She was one of the University's few women graduates at the time, and among the first trained parasitologists in Queensland. She started her career as scientist-in-charge at the Tick Biology Station in west Burleigh, conducting research into cattle tick life cycles and distribution. After the station closed, she moved to Nambour and worked as a microscopist with the Australian Hookworm Campaign, also identifying filarial and malarial parasites and studying mosquitoes. In 1923 she married a farmer, Peter McKeon, with whom she had five children. After losing their farm during the Depression, the McKeons settled in Toowoomba, then later retired to Point Vernon near Hervey Bay. There, Gwladys pursued marine biology, collecting and documenting seaweeds and marine invertebrates and sending her collections to specialists around Australia. She published an illustrated handbook, Life on the Australian seashore, in 1966 and donated its royalties to the Women's College at the University of Queensland. She died in Brisbane on 15 August 1979.