Arthur Lett-Haines (1894 – 25 February 1978), known as Lett Haines, was a British painter and sculptor who experimented in many different media, though he generally characterised himself as "an English surrealist". He was part of a London artistic circle, which included D. H. Lawrence, the Sitwells and Wyndham Lewis.
Arthur Lett was born in 1894, the son of Charles Lett and Frances Laura Esme Lett (who afterwards married S. Sidney Haines). He was educated at St Paul's School.
In the First World War he served in the British Army.
In 1916 Lett-Haines married Gertrude Aimee Lincoln at Hailsham, but when he met the painter Cedric Morris in 1918, the latter moved in with them and in 1919 his wife Aimee left on her own for America. Morris and Lett-Haines lived together until his death, Haines largely subordinating his own artistic career to promote that of his partner. This relationship lasted some 60 years, despite its open nature that included attachments on both sides such as Haines' affair with the artist and author Kathleen Hale.
After initially living at Newlyn, they moved to Paris in 1920, becoming part of an expatriate artistic community that included Juan Gris, Fernand Léger, Marcel Duchamp, Man Ray, Nancy Cunard and Ernest Hemingway. They returned briefly to London in 1926, before moving in 1929 to Suffolk.
In 1937, Morris and Haines founded the East Anglian School of Painting and Drawing at Dedham. When it burned down in 1939, the school was relocated to Benton End, a mansion near Hadleigh. Operating on a live-in basis that mingled artistic development with a social circle, its pupils included Lucian Freud, Bettina Shaw-Lawrence, David Kentish, Maggi Hambling, David Carr, Joan Warburton and Glyn Morgan.
In 1946, along with Henry Collins, Cedric Morris, John Nash and Roderic Barrett, Lett Haines became one of the founders of Colchester Art Society and later the Society's President.
The school closed when Haines died in 1978, though Morris continued to live at Benton End until his death in 1984.