Analysis of the (F606W – F850LP) colours with SSP EMILES models. Left panel: observed (F606W-F850LP) colour at z = 0.45 for an SSPburst as a function of the age of the SSP model. Right panel: observed (F606W-F850LP) colour at z = 0.55 for an SSP burst as a function of the age of the SSP model. The five different lines cover a range in metallicities from −0.96 to +0.25. The blue and red vertical histograms represent the probability density of the observed F606W-F850LP colour in the real Type-III S0 galaxies at 0.4 < z < 0.5 (left) and 0.5 < z < 0.6 (right), for the inner and the outer regions with respect to the R_break. The horizontal dashed and dotted lines represent the median (F606W-F850LP) values of the inner and outer profiles of our data, respectively. We refer to the legend in the panels for a key of the different lines.