  We show that, there exists a constant $a$ such that, for every subgroup $H$
of a finite group $G$, the number of maximal subgroups of $G$ containing $H$ is
bounded above by $a|G:H|^{3/2}$. In particular, a transitive permutation group
of degree $n$ has at most $an^{3/2}$ maximal systems of imprimitivity. When $G$
is soluble, generalizing a classic result of Tim Wall, we prove a much stroger
bound, that is, the number of maximal subgroups of $G$ containing $H$ is at
most $|G:H|-1$.
