  We present optical spectroscopic data for a complete sample of 161 S_5GHz >=
0.2 Jy, flat-spectrum radio sources. The sources were observed as part of a
survey for high redshift, radio-loud quasars, and were selected for
spectroscopic follow-up based on criteria of red optical colour and unresolved
optical counterpart, as measured from APM scans of POSS-I plates. 13 objects
from the spectroscopic sample were found to be radio-loud quasars with z > 3,
of which two were previously known. We give positions, E (red) magnitudes, O-E
colours, 5GHz radio fluxes, radio spectral indices, optical spectra and
redshifts where possible for the spectroscopic sample. We also give finding
charts for the z > 3 QSOs. The highest redshift object found is a QSO with z =
4.30 (GB1508+5714, the subject of an earlier Letter). The sample also contains
a z = 3.05 QSO, GB1759+7539, which is optically very luminous (E=16.1). In
addition, spectra are given for 18 S_5GHz >= 0.2 Jy, flat-spectrum radio
sources that do not form part of the complete sample.
