J, J − K_s colour–magnitude diagram of the central field of the Quintuplet cluster. L′-excess sources derived from Fig. 15 are marked as red diamonds, while Wolf-Rayet candidates are marked in blue. Proper motion members are shown in green, while non-members are shown in red and sources with unknown membership in black. The imposed magnitude limit to allow for proper-motion member selection, K_s< 17.5 mag, is shown as a dotted line. The horizontal dashed line marks the J-band completeness limit at J = 22 mag above which the combined cluster excess fraction was derived. The vertical dashed lines indicate the main-sequence colour selection applied in addition to the proper motion membership criterion to select the main-sequence reference sample to calculate the disc fraction. The J, J − K_s colour–magnitude diagrams of the outer fields can be found in Appendix (B.3).