  We combine the QSO samples from the 2dF QSO Redshift Survey (2QZ) and the
2dF-SDSS LRG and QSO Survey (2SLAQ) in order to investigate the clustering of
z~1.4 QSOs and measure the correlation function. The clustering signal in
z-space, projected along the sky direction, is similar to that previously
obtained from 2QZ alone. By fitting the z-space correlation function and
lifting the degeneracy between beta and Omega_m_0 by using linear theory
predictions, we obtain beta(z=1.4) = 0.60+-0.12 and Omega_m_0=0.25+-0.08,
implying a value for the QSO bias, b(z=1.4)=1.5+-0.2. We further find that QSO
clustering does not depend strongly on luminosity at fixed redshift. This
result is inconsistent with the expectation of simple `high peaks' biasing
models where more luminous, rare QSOs are assumed to inhabit higher mass
haloes. The data are more consistent with models which predict that QSOs of
different luminosities reside in haloes of similar mass. We find that halo mass
does not evolve strongly with redshift nor depend on QSO luminosity. We finally
investigate how black hole mass correlates with luminosity and redshift and
ascertain the relation between Eddington efficiency and black hole mass. Our
results suggest that QSOs of different luminosities may contain black holes of
similar mass.
