Metallicity as a function of ΔG = ΔF275W, F814W is plotted for the primordial populations P1 in all clusters in our sample with available UV photometry. The black lines show a linear fit (with the length being the FWHM of the distribution) and values are given for the fitted slopes m, the Spearman correlation coefficients r_S, and the differences Δ in metallicity between the extremities of the black lines. Note that for NGC 6388 and NGC 6441 not the full ranges are shown.