the log L(\[OIII\]) distributions in Fig. 4(b) of Kim et al. (2006), we infer for this particular luminosity-limited sample a median log L(\[OIII\])=41.1, which translates into log L$_{\rm{X}}=42.25$ and hence boosts the pre-factor of our assumed SFR(L$_{\rm{X}}$,z) relation from 0.63 to 2. A scatter of 1 dex is assumed on the SFR(L$_{\rm{X}}$,z) relation and the star-formation rates are assumed to decline as $(1+z)^{-7.9}$ at $z > 4.8$ following the assumed evolution of the global star formation rate density. SEDs for the star formation component are assigned from the Rieke et al. (2009) library, using the relation given by Yun, Reddy & Condon (2001) (their eqn. 13) to relate the star formation rate and 1.4 GHz radio luminosity; the far-infrared–radio relation (eqn. 1) was then used to assign L(FIR) and hence an appropriate template from the Rieke library using Fig. \[fig:LTIRtoFIR\_Rieke\].

Radio-loud AGN
--------------

Radio-loud AGN were modelled by W08 using the Willott et al. (2001) 151 MHz luminosity function comprising a weakly-evolving low luminosity component and a rapidly-evolving high luminosity component, identified with FRI and FRII radio sources, respectively. We consider them separately for the purposes of infrared SED assignment.

### FRIs

There is scant evidence for the presence of 