When did roald dahl put dead rat in a jarof gobstoppers?

Roald Dahl included a dead rat in a jar of gobstoppers in his book "Charlie and the Chocolate Factory," which was published in 1964. This incident is part of a scene that highlights the unsanitary and unethical practices of the fictional candy manufacturer, Willy Wonka, before he shifts to creating more magical confections. The moment serves to illustrate the contrast between the poor quality of some candies and the wonder of Wonka's factory.