Left: the redshift evolution of the B band mass-to-light ratio. The full black lines show the simple stellar population (SSP) predictions for a Salpeter IMF and formation redshift of either z_f = 2 (lower) or 2.5 (upper curve) and solar metallicity from Maraston (2005). The blue line shows the SSP for z_f = 1.5 and twice-solar metallicity, the magenta line the SSP for z_f = 2.5 and half-solar metallicity. The dotted line shows the best-fit linear relation and the 1σ errors dashed. Right: the (absence of) correlation of the M/L residuals Δlog M/L_B + 0.54z with cluster velocity dispersion. Black points are EDisCS clusters with HST photometry, cyan points with VLT photometry. Each EDisCS cluster is identified by its short name for clarity, see Table 4 for the full name. Red points are from the literature, Bender et al. (1998) and van Dokkum & van der Marel (2007). Cluster velocity dispersions come from Halliday et al. (2004) and Milvang-Jensen et al. (2008) for EDisCS clusters and from Edwards et al. (2002) (Coma), Le Borgne et al. (1992) (A2218), Gómez et al. (2000) (A665), Carlberg et al. (1996) (A2390), Fisher et al. (1998) (CL1358+62), Mellier et al. (1988) (A370), Poggianti et al. (2006) (MS1054-03 and CL0024+16), van Dokkum & van der Marel (2007) (3C 295, CL1601+42, CL0016+16), Tran et al. (2005) (MS2053-04), Jørgensen et al. (2005) (RXJ0152-13), and Jørgensen et al. (2006) (RXJ1226+33) for the literature clusters. We estimate σ_clus for RDCS1252-29 and RDCS084+44 from their bolometric X-ray luminosity and the relation of Johnson et al. (2006). Circles indicate clusters at redshift  > 0.7.