In the 1960s the forms in Frost's paintings became much simpler and the colours more pure. This reflected the art of the period and, in particular, paintings by the American artist Ellsworth Kelly. Kelly produced shaped canvases painted in single colours, which Frost might have seen in America.
Although paintings such as these are apparently abstract, Frost did relate the shapes to objects such as boats or women's bodies. A relief version of this work was sub-titled 'Mae West' after the famously curvy actress.