We present K-band photometry of the objects in the spectroscopic redshift survey of Colless et al. The absolute K magnitudes of the objects are inconsistent with the no-evolution or pure luminosity evolution models, regardless of model normalization, showing an excess of intrinsically faint galaxies at intermediate redshifts (z ≈0.4) with very blue colours. Many of these faint blue galaxies do not have strong emission lines, and it is argued that unidentified galaxies in faint redshift surveys could also be at intermediate redshift. It is argued that the excess faint blue galaxies seen in the B -band number counts at intermediate magnitudes and redshifts are a population of dwarf galaxies undergoing, or seen shortly following, a starburst in which supernova-driven winds blow out the gas of the galaxy, quenching the star formation and eliminating the emission lines.