  The excess numbers of blue galaxies at faint magnitudes is a subject of much
controversy. Recent Hubble Space Telescope results has revealed a plethora of
galaxies with peculiar morphologies tentatively identified as the evolving
population. We report the results of optical spectroscopy and near-infrared
photometry of a sample of faint \HST galaxies from the Medium Deep Survey to
ascertain the physical properties of the faint morphological populations. We
find four principal results: Firstly that the population of objects classified
as `peculiar' are intrinsically luminous in the optical ($M_B\sim -19$).
Secondly these systems tend to be strong sources of [OII] line luminosity.
Thirdly the optical-infrared colours of the faint population (a) confirm the
presence of a population of compact blue galaxies and (b) show the stellar
populations of Irregular/Peculiar galaxies encompass a wide range in age.
Finally a surface-brightness comparison with the local galaxy sample of Frei et
al shows that these objects are not of anomalously low surface brightness,
rather we find that all morphological classes have evolved to a higher surface
brightness at higher-redshifts ($z>0.3$).
