He was one of the first British artists to dismiss representation in favour of painting purely abstract images. Johnstone's work was closely associated with modernism, as he moved away from direct representation and toward abstraction.

William Johnstone OBE, 1897-1987

Johnstone, born at Denholm, near Hawick, Roxburghshire. had his interest in art encouraged by the watercolourist Tom Scott. He attended Edinburgh College of Art from 1919 to 1923, and in 1925 a travelling scholarship enabled him to study under André Lhote in Paris. He married and spent about a year in California and two or three years teaching art in Scotland before moving to London in 1931. He became Principal of Central School of Arts and Crafts in 1947, retiring in 1960. 
Johnstone was an inspired and influential teacher and writer on art, and in his paintings,  he was one of the most original artists of his generation. His work is almost wholly abstract, although much of it has a basis in landscape. Early in his career he developed a form of surrealistic abstraction, which later led on to a gestural expressionism.