Upper panel: likelihood distributions as a function of redshift for the individual galaxies (dotted lines); sum of the individual galaxy distributions (black-dashed line); and the product of the summed galaxy distributions multiplied by an indication of the cluster richness and gives the final likelihood distribution (solid magenta line). These curves are arbitrarily normalised so that they can be plotted simultaneously. Lower panel: number of galaxies that are most likely to be red sequence members at a given redshift.