a simple parameterization to allow us to compare the bulk properties of the galaxy populations.

An accurate determination of the point-spread function (PSF) is critical for this process, as galaxies at $z>1$ typically have half-light radii below 0.5 arcsec. Following the work of Lani et al. (2013), we investigated PSF variations across the UDS field and found that most variation occurred between WFCAM detector boundaries within the UDS mosaic (Casali et al. 2007). Testing revealed that we could obtain consistent results by splitting the UDS field into 16 overlapping sub-regions, corresponding to the $4\times 4$ WFCAM tiling pattern. Within each region the light profiles of approximately 100 stars were stacked to provide the local PSF measurement, with variations across the field in the range $0.75-0.81$ arcsec (FWHM). Considerable care was taken to mask sources in the vicinity of the stars used for PSF measurement.

From the resulting measurements of size and Sérsic index we rejected $\sim$9% of galaxies where GALFIT failed to converge on a Sérsic solution. The rejection rate was similar for the star-forming, passive and post-starburst populations. A further $\sim$1% of galaxies were rejected (a-priori) if the fits were formally very poor ($\chi^2_\nu>100$), which typically corresponded to highly 