in supercolour space, consistent with quiescent stellar populations in which a large fraction ($>$10%) of the stellar mass was formed within the last $\sim$1 Gyr, with the star formation then rapidly quenched (W14; see also Wild et al. 2016). The precise boundary between the passive and post-starburst population is set by the ability to observe strong Balmer absorption lines in optical spectroscopy (W14; Maltby et al. 2016). As outlined in Wild et al. (2016), evolutionary tracks suggest that not all photometric PSBs may have necessarily undergone a short-lived ‘burst’ of star formation. The population may also include galaxies that have undergone more extended ($\la$ 3 Gyr) periods of star formation, but the key characteristic is the rapid quenching of star formation within the last $\sim$1 Gyr.

In W14, four categories of star-forming galaxies were identified (SF1, SF2, SF3 and dusty), which we combine for the purposes of this work. As outlined in W14 (see also Section \[sec:uvj\]) the classification by supercolours is in very good agreement with the separation of galaxies using the more traditional rest-frame UVJ technique for separating star-forming and passive galaxies (Labbé et al. 2005; Wuyts et al. 2007). There is also good agreement with the UVJ 