Born in 1905 in Hoylake on the Wirral, Annie Myfanwy Delves was the daughter of accountant John Edwin Delves, and his wife Sarah Catherine Williams. At some point in her youth, her family moved to Deganwy in Caernarvonshire, a setting Delves would later use in a number of her books. She married Godfrey Edmund Fitzhugh in 1931, and had one son. Delves served in the ATS (Auxiliary Territorial Service) during the Second World War. She was divorced from Fitzhugh in 1948, and moved to Cork, where she lived until her death in 1959.
An author in the girls' school story genre, Delves' work is very much in the style of Angela Brazil.