After studying at the Edinburgh College of Art between 1932 and 1937, Gear (born at Methil, Fife) was given a travelling scholarship to Paris, where he began to study under Fernand Léger. Gear served in the Royal Signal Corps between 1940 and 1945 in the Middle East, Cyprus, Italy and finally in Germany. In 1946-47 Gear was stationed with the UK occupation forces in Germany, where he was the officer in charge of ensuring the security of art works in Lower Saxony under the auspices of the Allied Control Commission (Allied Control Commission, Monuments, Fine Arts and Archives Section). Gear had a studio in the castle at Celle and made friends with the painter Karl Otto Götz. In 1947 Gear moved to Paris, spending the following three years there. His studio was in the VIe Arrondissement, 13 quai des Grands Augustins. In Paris William Gear became acquainted with a cross-section of his European contemporaries, including Hartung, Soulages, Poliakoff, Mathieu, Atlan, Corneille, Constant, Stephen Gilbert, De Stäel and Vieira da Silva. Gear experimented with the techniques of Action painting. On his return to England, Gear had numerous exhibitions and received awards. In 1958 Gear became curator of the Towner [[sic!]] Art Gallery in Eastbourne, Sussex. He became head of the Faculty of fine Art at the Birmingham College of Art in 1964. Gear was a visiting professor at the Victoria National Gallery in Melbourne and at the University of Western Australia in Perth in1966. He also joined the Royal Birmingham Society of Artists in 1966. Gear was a recipient of the David Cargill Award from the Royal Glasgow Institute of Fine Arts in 1967. He lived at Edgbaston near Birmingham from 1975.
Between 1944 and 1988 Gear had thirty one-man shows of his paintings in Europe and elsewhere and was a member of Cobra, participating in many Cobra exhibitions. His style of painting evolved from a mainstream École de Paris fusion of naturalism and abstraction to a more delicate and abstract handling of colour in his late work. William Gear died in Birmingham in 1997.