Conrad is at war -- with his apathetic father, his insipid family and school life, his friends, and, ultimately, himself. He is fascinated with the power and violence of World War II, and he studies it intensely, building scale models of its engines of destruction. Death and human suffering, for him, are "quite different" from "killingm and armym and war."m
It's "Conrad at the controls" -- tyrannizing his old man, a pathetic, comic figure of a writer who scribbles sentimental plays "about nurses crying and people carrying on about sex." It's "Conrad in charge," for a time, at least, of his life and his fantasies. He imagines himself driving a British Centurion tank, surging with the tank's power, plowing over the countryside. He decides to build a full-scale version of the tank in the garage, as another less enterprising and less obsessed boy might build a go-cart.
The story and the fantsy turn when the dream-tank becomes real, and Conrad begins to "leak' through to another time, like the way a soggy liver sausage sandwich makes a wet hole in his lunch bag. Conrad finds himself back in World War II, the pilot of a now-real Avro Lancaster bomber, like the one he has glued together in another time and place from an Airfix model kit. Soon he discovers he is no longer the total master of his active, aggressive imaginings.
Andrew Davies' characterization of this inventive but alienated and cynical boy rings true. Conrad is typical of so many junior high school boys -- we've all known him, perhaps have been him once ourselves. Conrad's teachers think he is bright but needing to be "extended." Conrad's parents think his fixation on warfare is awful. Conrad thinks the adults in his life are ridiculous.