The fourth version of the theme of Orthogonal/Diagonal Composition, 1954 acquired by Tate in 1974. The Tate work and two smaller contemporary studies are executed in various combinations of oil and enamel on canvas, exploring different line widths as well as the reflective qualities of the materials. The present work was executed in 1974, twenty years after the first three, and is half the size of the Tate painting. It is realised in black tape applied to a primed canvas. Of the other two studies, one is in a private collection and the other in the collection of Southampton City Art Gallery. Hill revisited the topological theme of this work many times through his life. In the Hayward Gallery catalogue Alastair Grieve writes: ‘Orthogonal/Diagonal Composition seems to have been "programmed" by the joining of points of a right-angular grid orthogonally and diagonally and superimposing the nets. Unlike any work to date (1954) the composition is symmetrically balanced, it is a double square, but it is not, strangely, visually balanced and restful.' Version 4 had a similar talismanic presence to Frame and String Construction, 1948 and other works in Hill's living room in the Charlotte Street flat. He suggested that this may have been the first symmetrical work in Tate's collection.