What's ironic in Graham Greene's short story "The Destructors"?

It would seem
thatexpresses in his story, "" that the greatestof the World War II Blitz on London is
that the children of this era do not find destruction as an aberration. Rather, it seems to them
the norm.  This is why the boys who are lead, significantly, by an architect's son, imitate what
has occurred to buildings throughout their city; for Old Misery's house to be standing seems
somehow wrong to them. Their act of taking the house apart in such an ingenious way is, in
effect, an inverse form of architecture, a deconstruction.

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.

The underlying
climate of war is present in the descriptions:

• "They
  squatted in the ruins of the room...." Later, "the doors
  were all off,the furniture pillaged and ripped and
  smashed...."
• "...the slow warm drops...