Flora received her education at Surbiton High School before reading history at Newnham College, Cambridge.
Upon leaving she pursued a career in acting but recurring bouts of ill-health forced her to abandon this path.
She first published with a collection of short stories, ‘Mrs Hammond's Children’, in 1901 under the pseudonym Mary Strafford.
Her personal life was marred by tragedy with the death from typhoid, in India of her fiancé, the architect Ernest Shepherd, shortly before their wedding.
In 1913 ‘The Third Miss Symons’, was published, and perhaps her best-known work, ‘The Rector's Daughter’, in 1924.
Flora never married and lived most of her remaining years with her twin sister, Alice.
Flora M Mayor died in Hampstead, London on the 28th January 1932.