  We present the results of a study which uses the 3CRR sample of radio-loud
active galactic nuclei to investigate the evolution of the black-hole:spheroid
mass ratio in the most massive early-type galaxies from 0<z<2. Radio-loud
unification is exploited to obtain virial (line-width) black-hole mass
estimates from the 3CRR quasars, and stellar mass estimates from the 3CRR radio
galaxies, thereby providing black-hole and stellar mass estimates for a single
population of early-type galaxies. At low redshift (z<1) the 3CRR sample is
consistent with a black-hole:spheroid mass ratio of M_bh/M_sph ~0.002, in good
agreement with that observed locally for quiescent galaxies of similar stellar
mass (M_sph ~5x10^11 M_sun). However, over the redshift interval 0<z<2 the 3CRR
black-hole:spheroid mass ratio is found to evolve as M_bh/M_sph \propto
(1+z)^{2.07\pm0.76}, reaching M_bh/M_sph ~0.008 by redshift z~2. This evolution
is found to be inconsistent with the local black hole:spheroid mass ratio
remaining constant at a moderately significant level (98%). If confirmed, the
detection of evolution in the 3CRR black-hole:spheroid mass ratio further
strengthens the evidence that, at least for massive early-type galaxies, the
growth of the central supermassive black hole may be completed before that of
the host spheroid.
