Straight Rainbow was a proposal for a permanent large-scale work to be sited at Hillend, in the Pentland Hills, south of Edinburgh. I worked with the Physics Department at Heriot-Watt University to research the work. I proposed to create the illusion of a straight rainbow on the hillside as a striking visual presence that could be seen from miles around. The rainbow would be triggered by certain weather conditions and appear only fleetingly – like real-life rainbows – thus creating an ethereal monumental work.