"Spookiness"
In his introduction to this collection, Roald Dahl expresses his surprise at how many ghost stories do not contain an element of "spookiness," saying "I got a bit of a shock. The first batch of fifty or so stories I had read were so bad it was difficult to finish them. They were trivial, poorly written, and not in the least spooky. Spookiness is, after all, the real purpose of the ghost story. It should give you the creeps and disturb your thoughts." After reading a large number of ghost stories, Dahl finally came across "Harry," written by Rosemary Timperley, which finally had the element of spookiness he was looking for.
Imaginary friends
The theme of imaginary friends comes up frequently in this collection and is heavily associated with the supernatural. For example, in Timperley's story "Harry," the narrator introduces the story by telling us that her daughter had been speaking to an imaginary friend. Later, in a shock twist at the end of the story, Timperley subverts the idea of imaginary friends, creating a sense of dread and foreboding.
The Unknown
The creepiness of ghost stories often relies on mystery and an element of the unknown. This creates a feeling of apprehension and instability for the reader, who often does not know what to believe. For example, in "The Corner Shop" by Cynthia Asquith, at first, we do not know what is happening at the antique shop which creates a feeling of spookiness.
