Let $G$ be a simple classical algebraic group over an algebraically closed field $K$ of characteristic $p \ge 0$ with natural module $W$. Let $H$ be a closed subgroup of $G$ and let $V$ be a non-trivial irreducible tensor-indecomposable $p$-restricted rational $KG$-module such that the restriction of $V$ to $H$ is irreducible. In this paper the authors classify the triples $(G,H,V)$ of this form, where $H$ is a disconnected maximal positive-dimensional closed subgroup of $G$ preserving a natural geometric structure on $W$.