Bridget Riley is Britain’s most celebrated exponent of Op art, a movement which began in the 1950s principally through the work of the Hungarian-born French artist Victor Vasarely, though rooted in the work of the early 20th-century Italian artists known as the Futurists. Using purely abstract, geometric forms, ‘Op’ artists sought to create patterns which affected the optic nerves to induce sensations of movement or to suggest an intricate three-dimensional perspective on what was in reality a still flat surface.

In her early work Riley frequently used black and white or monochrome to achieve these effects. Often she produced a series of images relating to a single theme. In the suite of three prints, ‘Coloured Greys’, her use of colour is muted and subtle, but integral to the effect of light and movement, which appears to be related to the colour and movement of the sea.