Capel Boake spent most of her childhood living in Melbourne where her mother supported the family working as a photographer's assistant. She left school at an early age and worked as a shop-assistant, and subsequently as a secretary, a librarian, and a book-keeper, writing in her spare time. Although now largely forgotten, Boake was highly regarded by her fellow writers, and was generally well received by contemporary critics. She was a founding member of the Society of Australian Authors, regularly contributed verse and short stories to several periodicals including The Bulletin and The Australasian, and was also active in local literary circles. In 1939 she won a small Commonwealth Literary Fund grant, which enabled her to write The Twig Is Bent (1946). She is perhaps notable as one of the few Australian writers of her generation to fictionalise the everyday world of shop-assistants and secretaries, which she knew so well.
Capel Boake was a niece of the author Barcroft Boake.