Mary Valentine Ackland was born in 1906 to a wealthy family in London. She suffered an unhappy childhood which endured a convent education and culminated in marriage at 19 to a man with whom she was not in love. She refused to consummate the marriage, and it ended in annulment. She was a member of the communist party, and a journalist. A lesbian in a time which did not look kindly on such things, she found happiness in the arms of another poet, Sylvia Warner. After settling in the artistically prominent village of Dorset, the two collaborated on a book of poems entitleted "Whether a Dove or a Seagull" which was published in 1934. In 1935, they were unsucessfully sued for libel. In 1936, she defied British authority and along with her lover, aided the Spanish loyalists in their civil war. During the second world war, she worked as a civil defense clerk in England.

A second volume of poems, "The Nature of the Moment" was published posthumously in 1973 with an autobiographical memoir concerning her relationship with Warner following in 1985. She is primarily known as an early lesbian rights activist, as well as for her staunch criticism of Britain's policy of non-intervention during the Spanish Civil War.

She lived with Ms. Warner until her death in 1968 from breast cancer. Ms Warner passed away nine years later. Their ashes are buried together under a single stone in a Chaldon (Dorset) churchyard.