Quotients of permutation groups by nonabelian minimal normal subgroups

We prove that a quotient G/N of a subgroup G of Sym(n) by a nonabelian minimal normal subgroup N of G embeds into Sym(m) for some $m<n$. This result was proved previously by Robert Chamberlain, and we also prove that,if G is transitive, then we can take m \le 2n/5.