In Graham Greene's "The Destructors," discuss how Trevor overcame his circumstances.
I am uncertain as to the precise information you are asking for. Normally when we use the phrase "overcome circumstances" we are referring to a character, who, in spite of his poor upbringing or humble background, is nevertheless able to achieve something extraordinary or spectacular. This is hardly the case with Trevor. In fact, he is able to overcome his circumstances to commit an act of destruction that reveals more about the pent up anger inside of him and his nihilism than anything else.
Let us consider what we are told about Trevor's family background:
...the fact that his father, a former architect and present clerk, had "come down in the world" and that his mother considered herself better than his neighbours.
The name that he is given as well, Trevor, clearly marks him out as emerging from a different, higher class than the rest of the gang, which is why they have to call him T. The little information we are given about Trevor therefore shows that he has been raised in an atmosphere of lots of conflict and resentment, and, as a result, he may have a lot of pent-up anger. There is something ironic in the architect's son orchestrating the complete and total destruction of an architectural gem in London that has somehow managed to avoid being bombed.
Therefore Trevor doesn't really rise up above his circumstances - he wallows in them, using them as a source of rage and anger that he channels into destruction - for "destruction after all is a form of creation."