Colour composite images of the eight clusters in our sample created from the combination of the HST/ACS and WFC3 imaging. Circles show the multiple image positions used as model constraints in our strong lens modelling. We identify in white the families with spectroscopic redshift measurements and in green those for which the redshift value is a free parameter in our models (considered only in our silver sample, see Sect. 3 for more details). Blue boxes indicate the BCG positions.