Each character has a very specific, defined role in English society. For example, the Rogers come as servants, Vera as the secretary, and Anthony as the moneyed socialite. There is a doctor, a judge, a general, and a spinster, and each play out their roles exactly as they should – at least when they are first on the island. This IN this way, the novel establishes the rigidity of the English social order. And Then There Were None is set in 1930s England, a highly stratified society where one's social class could define one's life and relationships. The chaos and fear that comes to rule the island is the only thing that can break down these social and class barriers. Yet it is difficult for some of the characters to leave their expected roles, even when this puts them in danger. Mr. Rogers maintains his duties as servant even after his wife, along with some of the other guests, have been killed. He makes meals at the appropriate time, serves cocktail and even ventures out alone to chop wood for the guests – which leads to his death.
Agatha Christie sets up this rigid structure and maintains it for a while to demonstrate how difficult it is to break down the barriers set by class. When it does finally happen the characters don't only lose their social graces, they also begin to revert to an inhuman, animalistic state. They start eating out of cans in the kitchen, and leaving the house to find safety in nature. Vera even observes that the guests who have survived start to look more like animals. When their main worry is survival there is no time to worry about what is proper. Yet Agatha Christie shows that it takes something of the magnitude of being trapped on an island with an insane murderer to interfere with the class order of British society.