Distribution in the S₈₅₇/S₅₄₅ vs S₅₄₅/S₃₅₃ colour–colour plot of Planck-detected galaxies with S₅₄₅ ≥ 500 mJy. For this diagram we used the multi-band BeeP photometry (Planck Collaboration Int. LV 2020). Radio sources were removed by cross-matching the sample with the PCNT catalogue (Planck Collaboration Int. LIV 2018). The ten confirmed strongly lensed galaxies in this sample (filled blue circles) have colours at the red end of the distribution of the other galaxies (filled red squares). Still redder objects are likely GCC (see text).