  We present an analysis of the proximity effect in a sample of ten 2 A
resolution QSO spectra of the Ly alpha forest at <z> = 2.9. Rather than
investigating variations in the number density of individual absorption lines
we employ a novel technique that is based on the statistics of the transmitted
flux itself. We confirm the existence of the proximity effect at the > 99 per
cent confidence level. We derive a value for the mean intensity of the
extragalactic background radiation at the Lyman limit of J = 3.5^{+3.5}_{-1.3}
x 10^{-22} ergs/s/cm^2/Hz/sr. This value assumes that QSO redshifts measured
from high ionization lines differ from the true systemic redshifts by ~800
km/s. We find evidence at a level of 2.6 sigma that the significance of the
proximity effect is correlated with QSO Lyman limit luminosity. Allowing for
known QSO variability the significance of the correlation reduces to 2.1 sigma.
The QSOs form a close group on the sky and the sample is thus well suited for
an investigation of the foreground proximity effect, where the Ly alpha forest
of a background QSO is influenced by the UV radiation from a nearby foreground
QSO. From the complete sample we find no evidence for the existence of this
effect, implying either that J > 20 x 10^{-22} ergs/s/cm^2/Hz/sr or that QSOs
emit at least a factor of 1.4 less ionizing radiation in the plane of the sky
than along the line of sight to Earth. We do however find one counter-example.
Our sample includes the fortunate constellation of a foreground QSO surrounded
by four nearby background QSOs. These four spectra all show underdense
absorption within +/-3000 km/s of the redshift of the foreground QSO.
