The commission was for a pair of trellises to replace overburdened wooden trellises.
Unfinished mild steel was chosen. This would enable the steel to weather and rust, providing a texture to the surface which would allow climbing plants to grip.
Angled holes were drilled through square tube through which the mild steel rods were passed. Using a longer tube at the top and shorter tube at the bottom, the narrower spacing and resulting compression meant that the rods did not need to be fixed within the tubes.