  It has recently been argued that single-collapse high-redshift models for
elliptical galaxy formation can be rejected because they predict large numbers
of very red galaxies at intermediate redshifts which are not seen in deep
optical-infrared surveys. We argue, however, that this conclusion is premature
since, while much effort has been invested in refining the predictions of
hierarchical CDM models, only very simplistic models have been used to study
the evolution of galaxies in other cosmogonies (e.g. isocurvature models). We
demonstrate that the use of a more realistic multi-zone chemo-dynamical
single-collapse model, yields colours at intermediate redshifts which are much
bluer than inferred from the one-zone model, and indeed are comparable to those
predicted by hierarchical merging despite still allowing $> 90%$ of the final
stellar mass of elliptical galaxies to be formed in the first Gyr of their
evolution. We, therefore, conclude that the one-zone model should be avoided to
predict the colours of high-redshift galaxies and that the use of realistic
multi-zone models allows the existence of ellipticals at high redshift, being
their dismissal premature.
