  Further imaging observations of a sample of radio sources in the North
Ecliptic Cap are presented and a number of new identifications are made. Using
redshifts from spectroscopic data presented in a companion paper (Lacy et al.\
1999b), the photometric properties of the galaxies in the sample are discussed.
It is shown that: (1) out to at least z~0.6 radio galaxies are good standard
candles irrespective of radio luminosity; (2) for 0.6~<z~<1 a large fraction of
the sample have magnitudes and colours consistent with a non-evolving giant
elliptical, and (3) at higher redshifts, where the R-band samples the
rest-frame UV flux, most objects have less UV luminosity than expected if they
form their stellar populations at a constant rate from a high redshift to
$z\sim 1$ in unobscured star-forming regions (assuming an Einstein -- de Sitter
cosmology). The consequences of these observations are briefly discussed.
