In "The Rocking Horse Winner," what is the setting of the story? What is the moment when the story moves from history to action?

The setting of the story is in the family's "pleasant house, with a garden", where they lived in style, but were haunted by the lack of money.  Haunted, almost literally, as it reads that the house constantly whispered, "There must be more money". 

The story gives about 6 paragraphs of back-story and set-up, and moves directly from that history into action, when little Paul asks his mother why they don't keep a car of their own, but always use a taxi or their uncle's car.  From here there is a crucial discussion of money, and luck (which is, according to his mother, the ability to earn money). 

This story's themes of greedy matieralism and the fruitless quest for money make for a very sad, but though-provoking story, and that unique set-up is an important part of it.  I hope that helps!