"The Storyteller" by H.H. Munro (Saki) is a nested story, or a story within a story. The external story is "The Storyteller" itself, as it is told by Saki, where he narrates the events that are taking place with the aunt, the children, and the bachelor in the railway carriage. The internal story is the bachelor's tale.
This being said, Saki is the external narrator that, from a third person omniscient point of view, tells us the story of "a bachelor" who is aggravated by three misbehaved children, and by their aunt, who cannot control them with her boring stories. As a result, the bachelor decides to tell the children a story of his own; the crudeness and ironical nature of the story ends up fascinating the children.
This second, nested, story, told by the protagonist, makes the bachelor an internal narrator. The bachelor tells the children the fictional story about Bertha, the "horribly good" little girl whose good deeds and shiny medals of honor end up getting her eaten by a wolf.
Hence, "The Storyteller" is told from a third person omniscient point of view where Saki is the all-knowing and non-participant narrator. This point of view is focalized through the perspective of the bachelor as an internal narrator.