I think it is clear that Greene goes through great lengths to ensure that we as readers feel great sympathy for "Old Misery", or Mr. Thomas, and therefore, by default, this highlights the cruelty of the act of the boys in destroying his house. Consider the following quotation:
Mr. Thomas came out of the loo. He was wearing a gray blanket to which flakes of pastry adhered. He gave a sobbing cry. "My house," he said. "Where's my house?"
This sense of immense pity we feel for him is again emphasised by the laughter of the driver, who cannot help but laugh at the plight of Mr. Thomas:
"I'm sorry. I can't help it, Mr. Thomas. There's nothing personal, but you got to admit it's funny."
Clearly, therefore, our feelings about the boys are "guided" by this sad ending. We see them as "destructors" who have destroyed a man's life. However, at the same time it is important to realise that Greene again emphasises that they did not do this out of any sense of hatred - they did this because destruction is all their short lives have known, and thus whilst we feel angry, at the same time the anger is coupled with a sense of pity for these children of the war generation.
the whole story shows the impact of war in the society and exactly to the youngesters.
they are kin but the pressure make them angry, sad, fight lover and give them a sense to find justice in their society. they are young and full of anger and easily change their minds and decisions.they have no idea of war and just looking for justice through that hard situation.