  We compute the light hadron mass spectrum at beta=5.7 using the O(a) improved
Sheikholeslami-Wohlert (SW) fermion action with two choices of the clover
coefficient: the classical value, c=1, and a mean-field or tadpole-improved
estimate c=1.57. We compare our results with those of the GF11 Collaboration
who use the Wilson fermion action (c=0). We find that changing c from zero to 1
and 1.57 leads to significant differences in the masses of the chirally
extrapolated and strange pseudoscalar and vector mesons, the nucleon, the
Delta, and also in the Edinburgh plot. A number of other quantities, for
example m_V^2-m_PS^2, J, am_K/am_\rho and am_{K^*}/am_\rho do not appear to
change significantly. We also investigate the effect of changing the lattice
volume from approximately (2 fm)^3 to (2.6 fm)^3. We find that the meson masses
are consistent to within one standard deviation and baryon masses are
consistent to within two standard deviations.
