and star forming populations. Using the full spectral energy distribution (SED) fits to the ClG0218.3$-$0510 cluster members, we have converted the @Papovich2012 selection criteria to use our $i'$, $J$ and 3.6bands. Quiescent galaxies are those which satisfy the following (slightly stricter) criteria:

$$i'-J \ge 2.0$$

$$J-[3.6] \le 1.7$$

$$i'-J \ge 0.375+1.25 \times (J-[3.6])$$

We caution the reader that these equations were derived specifically for the eighth data release of the UDS and our data. The 3.6magnitudes may be systematically offset by up to 0.5mag due to the method by which they were determined and so these criteria may change for different datasets.

Figure \[fig:UVJ\] shows the distribution of all sources selected in 7C in $i'-J$ versus $J-[3.6]$ (rest-frame $U-B$ versus $B-J$) colour-colour space. The greyscale shows the expected distribution of the control field. The lines show the $i',J,[3.6]$ criteria used to select quiescent galaxies, which lie in the upper-left quadrant. The full cluster membership of 7C is not known, so interlopers were statistically removed in $i'J[3.6]$ colour-colour space using the UDS as the control field. To do this we use $\sim400$ random 0.9arcmin radius regions in the UDS, classifying sources as “quiescent" or “star forming" using the above criteria. Sources 