Major Harper

In the novel A Caribbean Mystery, Major Harper was an acquaintance of Miss Marple. He had been one of those quiet men with good manners, and one never knew what he was thinking about. He quietly cut his throat one day, and no one knew why. Miss Marple thought that she knew the reason, but she had never been quite sure.

Miss Marple thinks of Major Harper because Colonel Edward Hillingdon is similarly a quiet man with good manners.