  A graph $\Gamma$ is $G$-symmetric if it admits $G$ as a group of
automorphisms acting transitively on the set of arcs of $\Gamma$, where an arc
is an ordered pair of adjacent vertices. Let $\Gamma$ be a $G$-symmetric graph
such that its vertex set admits a nontrivial $G$-invariant partition ${\cal
B}$, and let ${\cal D}(\Gamma, {\cal B})$ be the incidence structure with point
set ${\cal B}$ and blocks $\{B\} \cup \Gamma_{\cal B}(\alpha)$, for $B \in
{\cal B}$ and $\alpha \in B$, where $\Gamma_{\cal B}(\alpha)$ is the set of
blocks of ${\cal B}$ containing at least one neighbour of $\alpha$ in $\Gamma$.
In this paper we classify all $G$-symmetric graphs $\Gamma$ such that
$\Gamma_{\cal B}(\alpha) \ne \Gamma_{\cal B}(\beta)$ for distinct $\alpha,
\beta \in B$, the quotient graph of $\Gamma$ with respect to ${\cal B}$ is a
complete graph, and ${\cal D}(\Gamma, {\cal B})$ is isomorphic to the
complement of a $(G, 2)$-point-transitive linear space.
