Trevelyan had no formal art training but joined Hayter's atelier in Paris in 1931 where he worked alongside artists such as Ernst, Kokoschka, Masson, Miró and Picasso. Trevelyan's work has always defied categorisation or pigeonholing and much of its interest derives from the apparently opposing instincts towards figurative realism and poetic fantasy. He was happily producing straightforward gouaches of Spain and the West of Ireland alongside Surrealist inspired painted wooden collages influenced by Paul Klee and Ben Nicholson. He was brilliantly inventive and possessed a wit and innocence of eye that could discover enchantment in the most mundane scenes.