  Submillimetre galaxies (SMGs) are among the most luminous dusty galaxies in
the Universe, but their true nature remains unclear; are SMGs the progenitors
of the massive elliptical galaxies we see in the local Universe, or are they
just a short-lived phase among more typical star-forming galaxies? To explore
this problem further, we investigate the clustering of SMGs identified in the
SCUBA-2 Cosmology Legacy Survey. We use a catalogue of submillimetre
($850\mu$m) source identifications derived using a combination of radio
counterparts and colour/IR selection to analyse a sample of 914 SMGs in the
UKIDSS Ultra Deep Survey (UDS), making this the largest high redshift sample of
these galaxies to date. Using angular cross-correlation techniques, we estimate
the halo masses for this large sample of SMGs and compare them with passive and
star-forming galaxies selected in the same field. We find that SMGs, on
average, occupy high-mass dark matter halos (M$_{\text{halo}}
>10^{13}$M$_{\odot}$) at redshifts $z > 2.5$, consistent with being the
progenitors of massive quiescent galaxies in present-day galaxy clusters. We
also find evidence of downsizing, in which SMG activity shifts to lower mass
halos at lower redshifts. In terms of their clustering and halo masses, SMGs
appear to be consistent with other star-forming galaxies at a given redshift.
