Top: metallicity distribution of IKN field RGB stars (solid, red-line histogram) and IKN GCs (labelled solid circles). For viewing purposes, the vertical position of the GCs is scaled according to their mass. Thick solid (black) and dashed (grey) curves are the scaled probability density estimate (ρ_⋆,RGB) and its 1σ estimated from the model PDFs (thin grey lines, details in Sect. 3.3). Bottom: mixture model of the IKN field RGB stars metallicity distribution. The best-fit maximum-likelihood mixture model probability density distribution is shown with the solid blue curve and its components by filled-curve Gaussians. For comparison we show again the metallicity distribution of IKN field RGB stars (solid red-line histogram). The percent fraction of each fitted Gaussian is given in the legend and Table 3.