  Only by incorporating various forms of feedback can theories of galaxy
formation reproduce the present-day luminosity function of galaxies. It has
also been argued that such feedback processes might explain the
counter-intuitive behaviour of "downsizing" witnessed since redshifts z=1-2. To
examine this question, observations spanning 0.4 < z < 1.4 from the
DEEP2/Palomar survey are compared with a suite of equivalent mock observations
derived from the Millennium Simulation, populated with galaxies using the
Galform code. Although the model successfully reproduces the observed total
mass function and the general trend of downsizing, it fails to accurately
reproduce the colour distribution and type-dependent mass functions at all
redshifts probed. This failure is shared by other semi-analytical models which
collectively appear to "over-quench" star formation in intermediate-mass
systems. These mock lightcones are also a valuable tool for investigating the
reliability of the observational results in terms of cosmic variance. Using
variance estimates derived from the lightcones we confirm the significance of
the decline since z=1 in the observed number density of massive blue galaxies
which, we argue, provides the bulk of the associated growth in the red
sequence. We also assess the limitations arising from cosmic variance in terms
of our ability to observe mass-dependent growth since z=1.
