Loyalty
One of the main themes of the story "The Destructors" is loyalty. Before Trevor becomes a member of the Wormsley Common Gang, their undisputed leader is a boy named Blackie, who is very much a "gang" boy. His priority is not so much his own position but cementing their gang as one of the forces on the street in the area. He wants to earn prestige for them with their exploits, and believes that the more they can prank people, the better known for it they will become amongst all of the other boy gangs in the area.
Blackie is hurt when the boys do not show him loyalty at his first confrontation with Trevor. Blackie does not want to destroy Mr Thomas' house and voices this, expecting the other boys to back him up and put Trevor's idea to rest. However, Trevor insists upon a vote, and the boys transfer their loyalty to him which is upsetting to Blackie who had previously believed they would show loyalty to him, and to the gang itself.
Towards the end of the story, when the boys are starting to rebel against Trevor's leadership, Blackie again demonstrates his own grasp of the concept of loyalty when he is loyal both to the mission of the gang, and to the boy who is now his leader. He realizes that demolishing the house will be the most notorious thing that the Wormsley Street Gang has done to date and his loyalty to furthering the future of the gang means that he is in full support of it. He also believes that they should remain loyal to the boy they have selected as leader and for this reason throws the full weight of his support behind Trevor. This is another example of the importance of loyalty as far as Blackie is concerned.
Class System in Britain
Britain was, and remains, a place with a deeply embedded class system, and it is enormously difficult for a person to cross from one class to another. A working class, destitute person can work their way out of poverty, and even become extremely wealthy, but they will never vault up to the upper middle or upper class. Similarly, an aristocrat or upper middle class family can be financially very poor, but even if they become destitute, they do not slip down the class rankings; they remain socially in the same place that they were on the day they were born.
This is precisely the principle that Trevor is protesting against with his destruction of the house. His opinion and philosophy doesn't represent the other boys - they just like tearing things down or causing trouble. Trevor, though, is symbolically tearing down the hierarchical history of social class that he hates. The house to him represents old money and by tearing it down he is tearing down the system that divides people by class. The fact that the truck driver laughs at the terrible wrong done to Mr Thomas indicates that this is not just something felt by the young and rebellious but something that has been a silent resentment within the working classes as a whole.
World War Two
Primarily because of the time of his writing them, many of the stories in this anthology have a World War Two theme. The central element of this theme is the German "Blitz" on the East End of London as they carried out nightly bombing raids to try to destroy the docks and the commercial areas of the city. The theme is shown in three different lights that are basically before, during and after the war. "The Destructors" has a Blitz theme in the way that it shows the years of devastation that occurred even a decade after the war had come to an end.
The boys meet every day on a vacant lot that used to be homes, but none have been rebuilt and the lot lies devastated and empty. There is only one house left on the street, the one belonging to Mr Thomas, and that has not been shored up or repaired either. The descriptions of the house imply that it is hanging on by a thread. This demonstrates the austerity that came into practice after the war when it was simply not possible to fund redevelopment for several decades.
