Born in Selsey Bill, West Sussex, but moved to London with his family soon after his birth. He had a younger brother and was brought up in Hampstead, London. His father left the family in 1918 when Keith was 6 years old. Vaughan went to school at Christ's Hospital, a public school in Horsham, where he was a boarder. While there he received tutoring in Italian Renaissance art. From 1931 to 1939 he worked as a trainee artist for the Lintas advertising agency. (Lever International Advertising Services, then owned by Unilever). He painted in his spare time.
During the Second World War he was a conscientious objector on humanitarian grounds and was conscripted into the non-combatant Pioneer Corps in the British Army (1941-1946) where he was engaged in hard physical labour and menial tasks. He was fluent in German and he was also employed as an interpreter for the prisoners of war in Yorkshire. He had access to many conscripts and prisoners of war who he used as models.
In 1942 he had his first one-man show of drawings at the Lefevre Gallery. Through another conscientious objector he met the art patron Peter Watson and publisher John Lehmann. John Lehmann commissioned him to do book illustrations and book jackets, and also encouraged him to write for Horizon and Penguin New Writing. Peter Watson introduced him to Neo-Romantic painters such as Graham Sutherland and John Minton. Keith Vaughan was influenced by their work.
After 1945 Vaughan travelled in the Mediterranean, North Africa, Mexico and the USA. From 1946 to 1948 he taught at Camberwell School of Arts and Crafts. During this time a penniless painting student, Ramsey McClure, turned up at his doorstep, and they became partners and lived together for 30 years. Keith Vaughan met many other gay figures from art and literature including Christopher Isherwood, and E M Forster.
From 1948 to 1957 Keith Vaughan taught at the Central School of Arts and Crafts. He painted the Theseus mural decoration in the Festival of Britain Dome of Discovery in 1951. He achieved some domestic stability with his partner, painting student Ramsay McClure. From 1954 he taught at the Slade School of Fine Art, where he taught David Hockney. He also travelled extensively and was visiting resident artist at Iowa State University during 1959.
His remarkable journal inspired by André Gide, reveals the tension in his life and work between intellectual puritanism and unrepressed sensuality. Like many gay men of his generation and class, Vaughan was troubled by insecurities about his sexuality. Much of what is known about his sexuality comes from his journals, which he began writing in August 1939 and continued until the morning of his death thirty-eight years later.
Vaughan's journals give insight into the relationships he had with other men, particularly with his working-class lovers, John McGuiness and Johnny Walsh, and his long-term companion and lover Ramsey Dyke Mclure. Like many middle-class gay men of his generation, he was attracted to an ideal of working-class masculinity.
A painter of figures and landscapes in oils and gouache, Vaughan was above all else enthralled by the male human body, and specialized in the depiction of male nudes in landscape, often naked and usually too indistinct to identify as individual portraits, in relation to his landscape, his environment, his space. Implicit in much of his work is man as a homosexual in opposition to his fellow man and a hostile world.
In 1962 a retrospective of his work was held at Whitechapel Art Gallery with an Arts Council tour. In 1964 he received an Honorary Fellowship from the Royal College of Art. Despite considerable success, including the award of a CBE in 1965, he became increasingly melancholic and reclusive. At the end of his life he struggled with cancer; after operations he could neither have sex nor paint, thus he brought his pain to an end and committed suicide by taking an overdose of drugs.
His journal, written from 1939 when he was 27, until his death in 1977, was edited by Alan Ross and published in 1989.