For anyone here who doesn't also read The Age of Uncertainty (and you really should--it's over there on the links bar, see?), the goodly proprieter has recently posted a series of excellent and thoughtful posts on the three John Christopher novels I discussed here earlier. The specific posts are here, here and here.
He also has a nifty Penguin cover for The Death of Grass which I'd never come across. I hope I can be forgiven for pinching it to show here: