Contours of the colour-magnitude diagrams of Flagship field galaxies (blue) and cluster (M_vir > 10¹⁴ h⁻¹ M_⊙) galaxies (red), at selected redshifts. The figure uses proxies for the rest-frame U − B and rest-frame B magnitude. The galaxies are limited to I_E < 24.5 and H_E < 24. The redshift bins have widths of ±0.05,0.06,0.07,0.1,0.2, and 0.2. The contours are spaced by 0.2 dex and are KDE-smoothed. The figure highlights how the Red Sequence is more prominent in clusters.