Born in Hammersmith, he attended the local art school before going on to the RCA in 1930. He began his teaching career at Croydon School of Art, going on to teach at the RCA from1948 to1975.
Initially influenced by Sickert and the Camden Town school, and the portraiture of the Euston Road School, his work often has a narrative quality, with elements of humour and affectionate satire. Wheelchair-bound due to childhood polio, much of his work took as its subject his immediate surroundings. He observed the local characters of Hammersmith with great interest and as a familiar local figure, was able to paint them relaxing in and around the local pubs, theatres and shops. A retrospective of Spear's work was held at the Royal Academy in 1980. His work is represented in the Tate Gallery Collection.