  Volonteri et al. (2011) found that the number of radio-loud quasars above
redshift 4 calculated from the luminosity function (based upon Swift/BAT
observations) is much smaller than the number estimated from the known
high-redshift beamed sources, blazars, assuming that for every beamed source
with a Lorentz factor of $\Gamma$, statistically $2 \Gamma^2$ non-beamed
sources should exist. To explain the missing misaligned (non-beamed) population
of high-redshift sources, they proposed various explanations, involving heavy
optical obscuration and significantly different Lorentz factors at early
cosmological epochs. Our EVN observations targeting high-redshift ($z>4$)
blazar candidates revealed 3 sources not showing relativistic beaming, but
rather kpc-scale double structures. These three sources have significant radio
emission resolved out with the EVN, while they are compact on $\sim 5-10$
arcsec scale. Our dual-frequency ($1.5$ and $5$ GHz) e-MERLIN observations of
these three sources revealed a rich morphology, bending jets, and hot spots
with possible sites of interaction between the jets and the surrounding medium
at intermediate scales.
