Kathleen Nott was born in London, England. Her father was a lithographic printer, and her mother ran a boarding house in Brixton. She was educated at Mary Datchelor Girls' School before attending King's College, London. She then won a scholarship to attend Somerville College, Oxford University, to read English Literature, but on arrival switched to Philosophy, Politics and Economics (PPE). In 1929, she married Christopher Bailey, an electronics and computer engineer whom she had met at Oxford. During the 1930s, she worked as a social worker and psychologist in London's East End of London, an experience that inspired her first novel, Mile End (1938). Her debut collection of poetry, Landscapes and Departures (1947), was well received. Her husband's work took them to the Netherlands, from which they escaped when Germany invaded in World War II. Her 1954 book The Emperor's Clothes brought her fame for attacking T.S. Eliot, Graham Greene, C.S. Lewis, among other dominant religious literary figures of the day. The following year, she began contributing book reviews, literary criticism, and essays to The Observer as well as to other leading publications such as Partisan Review, The Nation, Commentary, The Times and The Spectator. She also translated books and articles. She was elected a fellow of the Royal Society of Literature in 1977. She became involved in English PEN in the 1950s, becoming editor of the organization's journal, PEN Bulletin of Selected Books (later renamed PEN International) in 1960, and served as president in 1975. She was also president of the Progressive League and an honorary associate of the Rationalist Press Association.