In 1989, Willson was commissioned to paint the 'Cornucopia' mural by Speciality Shops, then owners of the Leeds Corn Exchange. The work is executed in the 'Keim' system of silicate paints, an extremely durable conservation paint system. Completed in autumn 1990 and unveiled by Patrick Nutgens.
"His paintings do not replace, de-nature or dissolve the wall; neither are they arbitrary easel paintings hung on it. Each is completely integrated into the architecture for which it is intended, with an enviable and exemplary alertness to the key features of its surroundings and to their potential for reassembly into powerful original composition."