Peter Ellenshaw was born in London, England but became best known as a California seascape and landscape artist, painting in a photorealist style. One of his earliest jobs was as an apprentice to W. Percy Day a British film special effects artist and painter. After serving in the Royal Air Force during World War II, Ellenshaw returned to the film industry as an artist for MGM. In the late 1940s Walt Disney offered Ellenshaw a position in the studio.

In 1953, Ellenshaw and his family moved to California. Ellenshaw began his career as a Disney illustrator and stage designer for Disneyland. Upon moving to California, Ellenshaw became entranced by the ocean and spent weekends painting the waves and beaches of the California coast. He also began a lifelong association with the Hammer Galleries in New York.

During the 1970s, Ellenshaw moved to Ireland, and he began a series of paintings of the green landscapes and Irish coastline. He exhibited works at the American Embassy in Dublin. Ellenshaw traveled throughout Europe and painted a famous painting at Giverny, France. He also painted in the Mojave desert, San Francisco, and New York. Ellenshaw finally settled in Santa Barbara, California where he continued to paint his famous seascapes of the Central California coastline.