Hughes trained at the Royal College of Art from 1946-50. He co-founded the Systems Group in 1969 whose work owed much to Constructivism developed in the period between 1917 and 1930. 'Systems' art is not concerned with objects but is an exploration of order, sequence, rhythm and structural relationships.
Hughes was very interested in the overlap between artistic and scientific endeavours. He once began a catalogue essay with a quotation from David Bohm (1968):
"... science, art and mathematics have thus been moving in related directions, towards the development of....a mode of experiencing, perceiving and thinking in terms of pure structure."
Hughes produced geometric, abstract, shaped canvases which reduced painting to a language of lines, angles and colours. Series II Green and Purple is a shaped composition based on a diagonal line, the interplay of the diagonal and vertical being a regular feature of Hughes' work.