Nicolette Macnamara was born into a decayed Anglo-Irish landowning family in County Clare, Ireland. Her parents separated when she was young, and she was raised with the neighboring family of the painter Augustus John. Her sister Caitlin grew up to marry the poet Dylan Thomas. Nicolette studied art at the Slade School of Art in London, where she met her future first husband, the artist Anthony Devas. She painted under her birth name Nicolette Macnamara, and achieved considerable success with her landscapes in watercolors and oils, exhibiting at the New English Art Club, the Royal Academy, and the London Group. World War II and the pressures of bringing up three young children seem to have been factors in her switch to writing. She produced two successful novels, Bonfire (1958), and Pegeen Cry-baby (1986), but was best known for two volumes of memoirs that focused on her relationships with her father, Francis "Frank" Macnamara, a poet, and Augustus John: Two Flamboyant Fathers (1966), and Susannah’s Nightingales (1978). She also gave talks on the BBC. Following the death of Anthony Devas, Nicolette remarried to the artist Rupert Shephard in 1965.