in the C field are then classified as “quiescent" or “star forming", and the quiescent fraction calculated as: $$f_{\rm Q} = \langle\frac{(N^{\rm 7C1753}_{\rm Q} - N^{\rm field}_{\rm Q})}{(N^{\rm 7C1753}_{\rm total} - N^{\rm field}_{\rm total})}\rangle_{\rm median}$$ where $N^{\rm field}_{\rm Q}$ is the measured number of rest-frame $UBJ$-selected quiescent galaxies in $\sim400$ random 0.9arcmin field regions. The uncertainty is the $1\sigma$ standard deviation in the calculated quiescent fractions for 7C.

Without far-IR data, we are unable to locate extremely dust-obscured systems, so these will not be found in either the C field or UDS and would be missing from Figure \[fig:UVJ\]. These extremely dusty galaxies are rare, but could be an important population in protoclusters [e.g. @Brodwin2013]. In addition, some galaxies (of order $\sim10\%$) may be misclassified due to very dusty regions within them. Further analysis with submillimeter data would be required to examine the extremely dusty populations in these fields. This means that we cannot analyse the extremely dust-obscured populations in any of the fields considered here, but we are able to do a robust comparison between them as the dusty populations are undetected in all of these fields: 7C, ClG0218.3$-$0510 and the UDS control field.

Half of the detected galaxies 