By the mid-1930s he was one of the leading British abstract artists, but by the end of the decade he had become disillusioned with non-representational art and reverted to naturalism. He concentrated on landscape and architectural views in an emotionally charged style that continued the English Romantic tradition (see Neo-Romanticism). Some of his finest works were done as an Official War Artist when he made pictures of bomb-damaged buildings. A similar stormy atmosphere pervades his famous views of country houses of the same period. Piper's work diversified in the 1950s and he became recognized as one of the most versatile British artists of his generation. He did much work as a designer of stage decor and of stained glass (notably at Coventry Cathedral) and was a prolific printmaker. In addition he made book illustrations and designed pottery and textiles. As a writer he is probably best known for his book British Romantic Artists (1942). He also compiled architectural guidebooks to several English counties, usually in collaboration with the poet John Betjeman.