Born the daughter of Joseph and Helen Cowen, Frances Cowen was educated in Oxford at an Ursuline convent and the Milham Ford School for girls.
She married George Heinrich Munthe in 1938; he died in 1941. They had one child, a daughter, Mary.
She wrote romantic suspense novels and books for children/young adults and produced more than 50 works under her own name. She also wrote around 10 novels under the pseudonym Eleanor Hyde.
In addition to writing, she worked for Blackwell's in Oxford, England, in 1938−39; was a member of Air Raid Precautions staff in Dartmouth, Devon, during World War II, and was assistant secretary for the Royal Literary Fund in London from 1955 through to 1966.
She contributed to various anthologies, to 'Good Housekeeping', 'Woman's Weekly', 'Oxford Times', plus other periodicals and newspapers. She was also a staff member of 'Little Folks' magazine and a member of PEN International and of the Crime Writers Association.