This became a compulsion which lasted for the rest of his life and his principal subjects were ships at sea and shipwrecks. The paintings were manifestations of memory and served as evocations of his time at sea, as well as of familiar land and seascapes around St Ives. Ignoring linear perspective he applied a perspective of his own to familiar subjects, working on whatever material or objects came to hand – not least because he could afford little else. Using a restricted palette he painted with varieties of ship paint on irregularly shaped card, often old grocery boxes, using the shape of the card to dictate the form and become as integral an ingredient as the colour or subject. What emerged was a systematic desire to record the passing of an era in which sail gave way to steam and the Cornish pilchard-fishing industry declined. His work and use of materials, and his emphasis on the painting as an object, were admired by Ben Nicholson (1894–1982) and Christopher Wood (1901–1930) who by 1928 were already attracted by the primitive. Despite their help Wallis died in poverty but his work is significant as an eloquent expression of a prevailing movement in English art.