g, (g − r) CMD of NGC188, with stars coloured according to which of the four evolutionary stages they are in for the purposes of the box and whisker plots of Figs. 18 and 19, and the discussion in Sect. 4.2. At the bottom right of the figure are the numbers of stars in each evolutionary stage. The small black dots are those stars which we excluded from further analysis. The isochrones plotted underneath are the same as those in Fig. 15.