Lines: expected growth curves as a function of cosmic time (or redshift) for massive haloes based on the Millennium simulation (Springel et al. 2005), in which we followed these haloes at fixed cumulative comoving number density. Red: the GCLASS cluster sample studied in vdB14. Black triangles: low redshift cluster sample studied here. Purple: the CNOC1 cluster sample studied by Muzzin et al. (2007). The cluster samples are linked by the evolutionary growth curves.