As in Fig. 18 but for [Fe/H] instead of age. Top panels: CMDs of NGC188, where each star is coloured by the most probable [Fe/H] value. Again only the stars shown as large circles are used to create the box and whisker plots below. Bottom panels: box and whisker plots of the most probable [Fe/H] values grouped by evolutionary stage. The whisker of the main sequence stars in the (g − z) plot extends beyond the bottom of the plot to [Fe/H] = −1.0.