Fiennes was born in Ealing in London and was the daughter of Alberic Fiennes, (1865–1919), who worked at the Bank of England and his wife Gertrude, the daughter of a Royal Navy officer.

[1] Fiennes studied at the Central School of Arts and Crafts and when she graduated began working for the Arts and Crafts Exhibition Society in London.

She produced a series of woodcut silhouette designs for the 1926 Golden Cockerel Press edition of The Fables of Aesop.

[3] In December 1932 Fiennes married Noel Rooke who had been one of her teachers at the Central School and was considered a leading light in the revival of wood engraving as a technique in Britain.

[2] In later life Fiennes turned from printmaking to concentrate on painting and in due course retired to a village near Banbury called Culworth where she died in 1998.