By 1964 Cohen’s paintings had become arrangements of distinctive marks, each with its own behaviour. In Next Year’s Valentine, 1964, a wash of mauve spreads across the bare ground; a scalloped dark green form, a loose dark brown grid and a looping red line are laid over it. At the right, a heart – the valentine of the title – is caught in a tighter red mesh and ringed with short radiating strokes. Each layer partly conceals and partly reveals what lies beneath.

Paintings of the same year, among them All Four and Search, were shown in Cohen’s survey at the Whitechapel Gallery in 1965, where John Richardson wrote that the latest pictures showed “one of the most serious and thought-provoking painters in England today.” The cartographic language of these canvases – contours, enclosed territories and lines of passage – returns after 1968 in the Contour Maps, Territorial Maps and Mazes through which Cohen first partitioned space by computer.