What is the author's style in The Open Window by Saki?

The most remarkable of Saki's devices in "The Open Window" is his construction of the story's narrative. The structure of the story is actually that of a story-within-a-story. The larger "frame" narrative is that of Mr. Nuttel's arrival at Mrs. Sappleton's house for the purpose of introducing himself to her. Within this narrative frame is the second story, that told by Mrs. Sappleton's niece.