Influenced by Henry Moore and Alexander Calder, he produced iron and stainless steel constructions suggestive of plant and insect forms.

Born in Buntingford, Hertfordshire, England. Butler was an architect by training (his work included the clocktower of Slough Town Hall, 1936), and architecture remained his main preoccupation until 1950, when he gave up his practice and became the first Gregory Fellow in Sculpture at Leeds University. He stayed at Leeds until 1953, when he suddenly came to prominence on being awarded first prize (£4,500) in the International Competition for a monument to The Unknown Political Prisoner , (defeating Calder, Gabo, and Hepworth among other established artists). The competition, financed by an anonymous American sponsor and organized by the Institute of Contemporary Arts, was intended to promote interest in contemporary sculpture and 'to commemorate all those unknown men and women who in our times have been deprived of their lives or their liberty in the cause of human freedom'. His design was characterized by harsh, spindly forms, suggesting in his own words 'an iron cage, a transmuted gallows or guillotine on an outcrop of rock'. The monument was never built (one of the models is in the Tate Gallery), but the competition established Butler’s name and he won a high reputation among British sculptors of his generation. He had learned iron-forging when he had worked as a blacksmith during the Second World War (he was a conscientious objector) and his early sculpture is remarkable for the way in which he used his feeling for the material to create sensuous textures.

Butler was an accomplished writer and radio broadcaster and he vigorously argued the case for modern sculpture. Five lectures he delivered to students at the Slade School in 1961 were published in book form the following year as Creative Development. He was a widely read man, who numbered leading intellectuals among his friends, and his liberal sympathies were shown by his donation of works to such causes as the campaign against capital punishment.