I think the conflict here is not between T and Old Misery, or even between T and Blackie. What is truly at issue is brokenness and desolation of England after the war, as contrasted with the values of pre-war Britain. In a sense, T's ascendency to the group's leadership is the result of a need for constructive action. Even Blackie, who at first is bitter over T's rise, realizes that being part of the project to carefully demolish Old Misery's house is more important than his ego. In this sense, the conflict is between the boys and the society that cannot support them, or the difference between the reality in which they have to live, and the expectations that are put on them.

In another sense, the story describes how even the best qualities of people can be turned against themselves. The demolition of the house is a kind of triumph, both of T's leadership, of the teamwork of the boys, and of T's engineering and architectural knowledge. The fact that this work has been done in the service of destroying the one intact house remaining in the village is a kind of bitter twist that suggests that in the new order, British qualities that had been used to build up communities will now be used to tear them down.

The conflict or tension in the short story “Destructors” is between creation and destruction. The story takes place in London in a post-war Britain. It is important to note that London had been bombed heavily by the Germans in WWII, hence the context after the war is one of building and, better yet, rebuilding.

The gang of boys, The Wormsley Common Gang, are bent on doing something. The newest member of the gang, Trevor (who is later simply called T.) has an idea. His idea is to destroy a stately house that has not been touched by the German bombings. The house is a venerable 200 year old building owned by a Mr. Thomas.

Once the boys commit to destroy the house, they are meticulous.

The dining-room was stripped of parquet, the skirting was up, the door had been taken off its hinge, and the destroyers had moved up a floor. Streaks of light came in through the closed shutters where they worked with the seriousness of creators - and destruction after all is a form of creation. A kind of imagination had seen this house as it had now become.

This description shows that the boys destroy with the precision and seriousness of creators. There is, of course, a paradox here. Something profound is going on. It would be wrong to think that the boys do this action purely out of mischief or hate. For example, they find money, but they do not take it. And later T. says that he has nothing against Mr. Thomas.

'Of course I don't hate him,' T. said. 'There'd be no fun if I hated him.' The last burning note illuminated his brooding face. 'All this hate and love,' he said, 'it's soft, it’s hooey. There's only things, Blackie,' and he looked round the room crowded with the unfamiliar shadows of half things, broken things, former things. 'I’ll race you home, Blackie,' he said.

Perhaps, the boys act in this way because all they ever saw was destruction. So, even while London is rebuilding, they are destroying. Herein lies the conflict.

There is also a strong element of class conflict in the story. The boys of the Wormsley Common gang are poor and working-class. Trevor, or T, originally comes from a fairly prosperous middle-class background. In order to fit in with the other boys in the gang he eggs them on to commit the mindless destruction of Mr. Thomas' house and to burn all his money. In leading the assault on the house, Trevor is finally rejecting his previous middle-class existence. He cannot stand the fact that he no longer has much in the way of material possessions and so feels deep resentment to those who do. His burning of Mr. Thomas' money in the mattress is his way of resolving what is clearly a deep internal conflict between his identity as a member of the Wormsley Common gang and his former self. This inner conflict mirrors the external class conflict between the working-class boys and Mr. Thomas, which manifests itself in the destruction of his property.

The conflict of the story "The Destructors" is creation versus destruction. The gang members in the story have grown up seeing the results of the blitz, the Nazi destruction of London and other parts of England through bombing. They gather at the beginning of the story at the car-park that is the site of the last bombing of the first blitz, and they set themselves to the task of destroying an old house that was supposedly built by Wren, the famous architect who designed St. Paul's. They choose this house in part because it was so ornately constructed that destroying it will be an act of creativity. As Greene describes their actions, "they worked with the seriousness of creators—and destruction after all is a form of creation." In other words, creation and destruction are two parts of the same process—a process that would have been very real to people in post-war London who created a new city in the parts of the old city that had been destroyed.

The conflict of "The Destructors" is primarily man vs. society.  The boys have had their innocence stripped by the events of World War II.  They use their imagination to reconstruct scenes of violence, demonstrating the influence of their environment on them.  The bombed out area in which they meet symbolizes this.  In addition to violence, the boys struggle to assert power and hierarchy, just as wars are fought for this purpose.