This painting brings together colour with broad horizontal bands with an active set of diagonals. The diamond format is spliced horizontally from corner to corner but the top and bottom triangles (which can be read as bands whose outer width meets the corner) are slightly wider - than the inner slices, visually compensating for their reduced area. The brown locks in to the strip of chromatic with tonal variations of green and blue bands. The left half of the variegated strip is black, which could be read as equally on the picture-surface as the other sombre slices, whereas the chromatic bands appear behind these them, glimpsed, shining forth through an aperture.
Discounting the width of the brown band up the lower right edge, the diamond is 'secretly' bisected from lower left to top right at the edge of the black triangle, though we would assume the visually active area around the light brown beside the pink to constitute that division. One then senses a whole diagonal organisation overlaid by horizontal bands. The title perhaps alludes to the diagonally thrusting effects of coloured light in Cologne's Gothic cathedral. Reference to the spiritual and a tense relationship the vertical and the diagonal indicate Tyzack's admiration for Barnett Newman, whose Chartres was produced in 1969.