  We present predictions for the structural and photometric properties of
early-type galaxies in the cold dark matter cosmology from the published
semi-analytical galaxy formation models of Baugh et al. and Bower et al. These
calculations were made with the GALFORM code, which tracks the evolution of the
disc and bulge components of a galaxy, using a self-consistent model to compute
the scalelengths. The sizes of galactic discs are determined by the
conservation of the angular momentum of cooling gas. The sizes of merger
remnants are computed by applying the virial theorem and conserving the binding
energy of the progenitors and their orbital energy. We compare the model
predictions with observational results derived from the SDSS. The model enjoys
a number of notable successes, such as giving reasonable reproductions of the
local Faber-Jackson relation, the velocity dispersion-age relation, and the
fundamental plane relating the luminosity, velocity dispersion and effective
radius of spheroids. These achievements are all the more remarkable when one
bears in mind that none of the parameters have been adjusted to refine the
model predictions. We study how the residuals around the fundamental plane
relation depend on galaxy properties. We examine in detail the physical
ingredients of the calculation of galaxy sizes. We also study the evolution of
the scaling relations with redshift. However, there are some important
disagreements between the predictions of the model and observations: the
brightest model spheroids have effective radii smaller than observed and the
zero-point of the fundamental plane shows little or no evolution with redshift
in the model.
