The active nuclei of z<1.0 3CRR radio sources
  We combine Chandra and XMM-Newton X-ray data from our previous papers with
new X-ray observations and with Spitzer mid-infrared data in order to study the
nature of the nuclei of radio galaxies and radio-loud quasars with z<1.0 from
the 3CRR sample. The significant increase in sample size over our previous
work, the reduction of bias in the sample as a result of new observations, and
the availability of more mid-infrared data allow us to show conclusively that
almost all objects classed as low-excitation radio galaxies in optical
spectroscopic studies lack a radiatively efficient active nucleus. We show that
the distribution of absorbing columns in the narrow-line radio galaxies differs
from the population of X-ray-selected radio-quiet type-2 quasars and from that
in local Seyfert 2s. We comment on the current evidence for the nature of the
soft X-ray component in radio-galaxy nuclear spectra, concluding that a jet
origin for this component is very hard to evade. Finally, we discuss the
recently discovered `fundamental plane' of black hole activity, showing that
care must be taken when placing radio-loud AGN on such diagnostic diagrams.
