What details in the introductory section and in the children's story imply the nature of the social order in which both occur?
I think that the presence of wealth and security in the face of a world in which these elements are perceived to be threatened are common threads in both the introductory story and the child's story that follows. For Gordimer in the introductory section of the story, there is a fear of the perceived criminal elements in the outside world infiltrating her own world and her own home. The creaking she hears she interprets to be a criminal. The reality is that the fears of the outside world enter the realm of the subjective. This is the same condition that the family in the short story share. While there is nothing that really indicates that they are under siege or in danger, there is a perceived threat or danger from the outside world and in this, there is a similar thread that ties both stories together. In both, the fear of "the other" drives individuals. What Gordimer realizes in the introductory story is what the family fails to do so. This is the idea that there is fear in the outside world and rather than capitulate to it, one of the precepts of the modern setting is to understand and accept this fear, while not letting it drive the individual. The sad story of the family would confirm this.