  We construct a sample of extremely red objects (EROs) within the UKIDSS Ultra
Deep Survey by combining the Early Data Release with optical data from the
Subaru/XMM-Newton Deep Field. We find a total of 3715 objects over 2013 sq.
arcmin with R-K>5.3 and K<=20.3, which is a higher surface density than found
by previous studies. This is partly due to our ability to use a small aperture
in which to measure colours, but is also the result of a genuine overdensity of
objects compared to other fields. We separate our sample into
passively-evolving and dusty star-forming galaxies using their RJK colours and
investigate their radio properties using a deep radio map. The dusty population
has a higher fraction of individually-detected radio sources and a higher mean
radio flux density among the undetected objects, but the passive population has
a higher fraction of bright radio sources, suggesting that AGNs are more
prevalent among the passive ERO population.
