Like the cubists, Nicholson was interested in the ways in which paintings can represent space. In the 1930s, he made shallow reliefs in which areas of different depths define actual space. In the most radical of these, colour was reduced to just white or grey to achieve a sense of purity. Depth and plain colour make the play of light and shadow an intrinsic part of the work. This emphasis was related to new ideas about living and, especially, to modern architecture, in which natural light and formal simplicity were major concerns.