The colour-magnitude relations of one of the most massive (� 10 15 M⊙), high redshift (z = 0.89) clusters of galaxies known have been studied. Photometry has been measured in the V, R, I, z, F606W, F814W, J and K bands to a depth of K � 20.5 = K ∗ + 2.5 and spectroscopy confirms 27 K band selected galaxies as members of the cluster. The V K colours are equivalent to a rest-frame colour of � 2700u J, and provide a very sensitive measure of star-formation activity. Hubble Space Telescope imaging with the Advanced Camera for Surveys has been used to morphologically classify the galaxies. The cluster has a low early-type fraction compared to nearby clusters, with only 33 per cent of the confirmed cluster members having types E or S0. The early-type member galaxies form a clear red-sequence in all colours. The scatter and slope of the relations show no evolution compared to the equivalent Coma cluster relations, suggesting the stellar populations are already very old at z = 0.89. The normalisation of the relations has been compared to models based on synthetic stellar populations, and are most consistent with stellar populations forming at zf � 3. Some galaxies of late-type morphology were found to lie on the red-sequence of the colour-magnitude relation, suggesting that they have very similar stellar populations to the early-type galaxies. These results present a picture of a cluster in which the early-type galaxies are all old, but in which there must be future morphological transformation of galaxies to match the early-type fraction of nearby clusters. In order to preserve the tight colourmagnitude relation of early-types seen in nearby clusters, the late-type galaxies must transform their colours, through the cessation of star-formation, before the morphological transformation occurs. Such evolution is observed in the late-types lying on the colour-magnitude relation.