Born in Manchester, Dewhurst spent his childhood here, later making a living locally as a writer and illustrator. Between 1891 and 1895 he studied art in Paris, where he particularly responded to the Impressionists in their use of bold colour and broken handling to convey the effects of light. In 1904, he published a book, 'Impressionist Painting', which was the first major British account of the subject. It argues the importance of Constable and Turner in the development of French Impressionist painting. This stance was refuted by Monet, Pissarro and others. Picnics were popular subjects with the Impressionists, reflecting a new hedonistic approach to the outdoors.