  We investigate the large-scale clustering of radio sources in the FIRST
1.4-GHz survey by analysing the distribution function (counts in cells). We
select a reliable sample from the the FIRST catalogue, paying particular
attention to the problem of how to define single radio sources from the
multiple components listed. We also consider the incompleteness of the
catalogue. We estimate the angular two-point correlation function $w(\theta)$,
the variance $\Psi_2$, and skewness $\Psi_3$ of the distribution for the
various sub-samples chosen on different criteria. Both $w(\theta)$ and $\Psi_2$
show power-law behaviour with an amplitude corresponding a spatial correlation
length of $r_0 \sim 10 h^{-1}$Mpc. We detect significant skewness in the
distribution, the first such detection in radio surveys. This skewness is found
to be related to the variance through $\Psi_3=S_3(\Psi_2)^{\alpha}$, with
$\alpha=1.9\pm 0.1$, consistent with the non-linear gravitational growth of
perturbations from primordial Gaussian initial conditions. We show that the
amplitude of variance and skewness are consistent with realistic models of
galaxy clustering.
