The aluminium piece installed in ‘Castrol House’ was the first open cast relief Clarke had ever done. The piece was cast in his barn studio at Stowe Hill, where the barn floor was covered to a depth of twelve inches with foundry sand. This was worked and reworked in reverse and intaglio three times, once each for the ground floor section of the relief, the stairwell section and the first floor section forming the back wall of an exhibition space.

After the sand had been worked, steel separation strips were arranged on top of the sand to form sections which could be cast in one pour from a crucible full of molten metal.

Each section of the mural was then cast and worked to obtain panels of even thickness and consistent texture and finish. The individual sections were then bolted in place on to a steel frame installed on the back wall of the foyer.