Colour-period diagrams for the four similarly-aged open clusters (varying colours) available to date, compared with the measured one for NGC 2516 (black in each panel). The clusters are (from top to bottom) M 35, M 45 (Pleiades), M 50, and Blanco 1, with E_{(B − V)} values taken from the respective publications, and scaled for Gaia colour. Note that their rotational distributions are visually essentially indistinguishable from that for NGC 2516 to within the sensitivities of the individual studies. (See Fig. B.1 in the appendix for the equivalent figure in B − V colour, and the text for further details).