  We present an analysis of the spatial clustering of a large sample of
high-resolution, interferometically identified, submillimetre galaxies (SMGs).
We measure the projected cross-correlation function of ~350 SMGs in the UKIDSS
Ultra Deep-Survey Field across a redshift range of $z=1.5-3$ utilising a method
that incorporates the uncertainties in the redshift measurements for both the
SMGs and cross-correlated galaxies through sampling their full probability
distribution functions. By measuring the absolute linear bias of the SMGs we
derive halo masses of $\log_{10}(M_{\rm halo}[{h^{-1}\,\rm
M_{\odot}}])\sim12.8$ with no evidence of evolution in the halo masses with
redshift, contrary to some previous work. From considering models of halo mass
growth rates we predict that the SMGs will reside in haloes of mass
$\log_{10}(M_{\rm halo}[{h^{-1}\,\rm M_{\odot}}])\sim13.2$ at $z=0$, consistent
with the expectation that the majority of $z=1.5-3$ SMGs will evolve into
present-day spheroidal galaxies. Finally, comparing to models of
stellar-to-halo mass ratios, we show that SMGs may correspond to systems that
are maximally efficient at converting their gas reservoirs into stars. We
compare them to a simple model for gas cooling in halos that suggests that the
unique properties of the SMG population, including their high levels of
star-formation and their redshift distribution, are a result of the SMGs being
the most massive galaxies that are still able to accrete cool gas from their
surrounding intragalactic medium.
