During the preliminary study that preceded the restoration, in 1993, of the chancel and transept of the chapel of Saint Joseph (the ancient chapel of Saint Ursula), a painted mural was discovered. It was removed in the winter of 1994-95 and placed on a masonry support south of the ambulatory. The mural contains an orange-yellow painting on a gray ground with black and white decoration. What at first sight appears to be a neglected finish, after closer examination and a little reflection, looks like the result of a perfectly admissible and coherent way of doing things. This mode of execution represents a very widespread concept of monumental painting in Belgium, chronologically as well as geographically. The aesthetic expression of these works does not permit indifferent retouching attempts, all the more since degradations emphasize their rather informal structure.