James Gunn was born in Glasgow where he attended the Glasgow School of Art from 1909. He fell out with the school’s director, however, and enrolled at the Edinburgh College of Art the following year, studying under Morley Fletcher and then at the Académie Julian in 1911, where he studied under Jean-Paul Laurens. Although he left Paris two years later, it was during his time in France and in Spain that he developed his particular approach to painting of applying the paint bluntly and freshly and regularly using a stark palette. During the First World War he served with the 10th Scottish Rifles and when the war had finished he married twice, first to Gwendoline Charlotte Thorne in 1919 and then Pauline Miller in 1929. Pauline was the model for some of his best-known paintings. In 1929 he also decided to devote himself entirely too painting portraiture and a successful career soon followed. He was prolific in his output, working on portraits of friends, family, politicians, judges, bankers and members of the Royal family.

Although his work was sometimes rejected by the Royal Academy, he was made an associate in 1953, the same year in which he became president of the Royal Society of Portrait Painters. In 1961 he was made a Royal Academician and he was knighted two years later. His striking portraits were often painted in sombre colours and always with close attention to detail.