In the 1920s and 1930s Jacob composed music for choral societies and school choirs, which provided a steady income, in between more ambitious compositions. From his works of the 1920s, Wetherell singles out a viola concerto (1926), a piano concerto followed (1927) and the First Symphony (1929) dedicated to the memory of Jacob's favourite brother who was killed in the First World War. Large-scale works from the 1930s include an oboe concerto for Léon Goossens (1935) and Variations on an Original Theme (1937)