Williams left Guyana at the height of the Independence Movement in 1952, and moved to the United Kingdom. Following his first exhibition in London in 1954, he became an increasingly significant figure in the post-war British avant-garde art scene, particularly through his association with Denis Bowen's New Vision Centre Gallery. In 1966, he came together with a group of London-based Caribbean artists and intellectuals to found the Caribbean Artists Movement, which served as a dynamic hub of cultural events and activity until its dissolution in 1972. From 1970 onwards, Williams worked in studios in Jamaica and Florida as well as the UK, and it was during this period that he produced three of his best-known series of paintings: "Shostakovich" (1969–1981), "The Olmec-Maya and Now" (1981–1985) and "Cosmos" (1989).