The Great Recession
In late Victorian times, Britain was in the throes of a Great Recession that was responsible not just for a fall in the fortunes of the House of Bastable, but a fall in the fortunes of many other houses as well (such as the Bastables' neighbors.) The effects of this fall in fortune is one of the main themes of the novel. The children's father has great difficulty in keeping up with his financial obligations and everything that was not completely necessary was cut out of the family's economy. The country's recession also opened the door to con-men and swindlers who were able to offer schemes to "get rich quick" that only made things worse.
Culpability of Newspapers In Conning The Public
E. Nesbit was concerned about the way in which the print media enabled get rich schemes to flourish primarily by publishing them throughout the newspaper even though they were well aware that the schemes were a con. This is substantiated by the children's visit to the newspaper editor who will not let them invest in one of the schemes, as he knows they are just kids and does not want them to lose their money on what he knows to be a swindle. This sensibility does not extend to his adult readers, unfortunately, and throughout the book the author returns to the theme of get rich quick schemes being published in the newspapers who get away with promoting them knowing that they are fake.
The Importance of Family
The Bastables are a close-knit and loving family and the importance of this is one of the themes that runs throughout the novel. The children work as a team and rather than feeling that their father is responsible for restoring the financial well-being of the family, they take responsibility for helping as well and try to solve the situation themselves. This demonstrates their loyalty to both their father and to each other, and the family unit. Oswald, as the narrator, never says that his father's fortunes had failed, but that the family's have, which also indicates the importance of thinking as a family unit rather than as individuals. The children are always thinking of each other's well-being which shows what a strong and united family they are.
The Importance of Doing The Right Thing
One of the underlying themes of the novel is the importance of doing the right thing which is illustrated in the failure of all of the "wrong things" that the children try, and the fact that they never make money from "ill gotten gains". They are terrible kidnappers, they fail miserably as highwaymen, and their attempts to blackmail a burglar do not net any money either. By contrast, their generosity to a man they believe to be poor even when they are struggling financially themselves eventually brings the greatest reward not just in an extended family with an uncle who loves them, but in financial riches beyond their wildest dreams, because their new uncle turns out to be very rich indeed.
Social Expectation and Financial Shame
The Bastables were ashamed of their financial situation and this is not something that would have been specific to them as there was enormous social expectation to keep up the appearance of affluence in their social bracket. This is another theme that is central to the novel and also central to the author's own belief that social snobbery was too much of an influence in Victorian society. There are many examples of the family trying to hide their fall in fortunes, for example, telling people that they were taking a holiday from school, rather than admitting that they could not afford to go. Their neighbors were also experiencing a fall in fortunes, and went so far as to pretend to go on vacation as usual, sneaking back into the house under cover of darkness and being mistaken for burglars, rather than admitting that they could not afford to take a vacation that summer.