  We analyse 850um continuum observations of eight massive X-ray detected
galaxy clusters at z~0.8-1.6 taken with SCUBA-2 on the James Clerk Maxwell
Telescope. We find an average overdensity of 850um-selected sources of a factor
of 4+/-2 per cluster within the central 1Mpc compared to the field. We
investigate the multiwavelength properties of these sources and identify 34
infrared counterparts to 26 SCUBA-2 sources. Their colours suggest that the
majority of these counterparts are probable cluster members. We use the
multi-wavelength far-infrared photometry to measure the total luminosities and
total cluster star-formation rates demonstrating that they are roughly three
orders of magnitude higher than local clusters. We predict the H-band
luminosities of the descendants of our cluster submillimetre galaxies and find
that their stellar luminosity distribution is consistent with that of passive
elliptical galaxies in z~0 clusters. Together, the faded descendants of the
passive cluster population already in place at z~1 and the cluster
submillimetre galaxies are able to account for the total luminosity function of
early-type cluster galaxies at z~0. This suggests that the majority of the
luminous passive population in z~0 clusters are likely to have formed at z>>1
through an extreme, dust-obscured starburst event.
