Vertex-quasiprimitive locally primitive Graphs

It is known that finite non-bipartite locally primitive arc-transitive graphs are normal covers of ‘basic objects’—vertex quasiprimitive ones. Praeger in (J London Math Soc 47(2):227–239, 1993) showed that a quasiprimitive action of a group G on a nonbipartite finite 2-arc transitive graph must be one of four of the eight O’Nan–Scott types. In this paper, we classify the basic locally primitive graphs where the action on vertices has O’Nan–Scott type HS\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{HS}$$\end{document} or HC, extending the well-known Praeger’s result about ‘basic’ 2-arc transitive graphs.