  We have modelled the light distribution in 10095 galaxies from the Millennium
Galaxy Catalogue (MGC), providing publically available structural catalogues
for a large, representative sample of galaxies in the local Universe. Three
different models were used: (1) a single Sersic function for the whole galaxy,
(2) a bulge-disc decomposition model using a de Vaucouleurs (R^{1/4}) bulge
plus exponential disc, (3) a bulge-disc decomposition model using a Sersic
(R^{1/n}) bulge plus exponential disc. Repeat observations for 700 galaxies
demonstrate that stable measurements can be obtained for object components with
a half-light radius comparable to, or larger than, the seeing half-width at
half maximum. We show that with careful quality control, robust measurements
can be obtained for large samples such as the MGC. We use the catalogues to
show that the galaxy colour bimodality is due to the two-component nature of
galaxies (i.e. bulges and discs) and not to two distinct galaxy populations. We
conclude that understanding galaxy evolution demands the routine bulge-disc
decomposition of the giant galaxy population at all redshifts.
