Coker first studied at St Martin’s School of Art (1941-43; 1947-50), and began to exhibit regularly at the Royal Academy from 1950. He became associated with the Kitchen Sink realist painters, exhibiting at Zwemmer Gallery from 1956. But this association was short-lived and from the time of his first Zwemmer exhibition, he was already moving into landscape painting. Coker's development as a landscape painter originated in his first encounter with the canvases of Gustave Courbet on a trip to Paris in 1950. Coker is known for his use of bold colours in his landscapes, thick impasted paint to capture the power of natural forces. He painted throughout the UK and particularly favoured northwest Scotland towards the end of his life.