Fanny was the fifth child and third daughter of George, the son of John Burnell of Guisely, Yorkshire, England, who brought his family of six daughters and two sons to South Australia in the ship Florentina in 1849. Her mother was Eliza Ann Mitton. Although Fanny was born in Victoria, the family lived in Hindmarsh, Adelaide, and she went to school locally in about 1872-1873, where a Mrs Santo, wife of a doctor, was just starting a school for young ladies. She later attended two other schools for short periods. She married in 1884 at the age of 23 .
Her husband was 'often unwell unless he could get to the seaside every few weeks' (The Burnells p 147), so she and her husband lived at the Grange after the birth of their first baby. They later built in John Street, Hindmarsh, where they lived for ten or eleven years. They had three children. They went farming for several years on Eyre Peninsula, 'for the boys', but after suffering two devastating bushfires they returned to the city. Fanny won several prizes for oil paintings. She also wrote the family history of the Burnell family 1849-1948, in which she iincluded her memories of early days and members of the family. This book identified her as the author of Shots and Strokes in Croquet, published in 1948 under the name 'Fanwy Llyn'.
