the background design is based on kempe's ‘the four rivers window’ in st mary's priory church, monmouth. a celtic knot pattern gradually rises from green (earth) through blue (sky) to purple (heaven). these intertwining lines were also used by the hereford school of romanesque sculptors who were involved with the priory at the end of the 11th century. a beaded motif from one of the capitals is used in the lower panels of each of the background.