Christopher's prequel is a kind of invitation to the trilogy, written for slightly younger readers and in 1988, exactly twenty years after the originals. It has less adult depth than the original, yet even so it deals with divorce and family death as minor themes along the way, and it's thoroughly readable.
Science fiction readers have long been embarrassed by unnecessary sequels damaging their originals: Isaac Asimov's attempt to revisit Foundation, Anne McCaffrey's ever more juvenile Dragon books, Robert Heinlein's dreadful attempts at making all his past characters meet in a sort of land of fiction, even Arthur C. Clarke's several tries to recapture the spirit of Rendezvous With Rama. It was a shrewd decision on Christopher's part to write not a sequel to, or a redundant cutaway from the main trilogy, but instead to write a work at a kind of careful distance from the original. The action takes place a century before, in the modern world, and of course no characters are in common between this and the original books.
By design, then, When The Tripods Came adds nothing to the main trilogy and doesn't oblige us to re-interpret it. On the other hand, it is laced through with references ahead, so to speak. We begin with two young heroes, Laurie and Andy, obliged to grow up in a hurry: later we meet Rudi, who rescues them. In one of the concluding passages, Laurie speculates about the resistance which they are just beginning to form.
I wondered about those who would come after -- if maybe one day three like us would lie on this hillside in the sun, watching butterflies as we were doing...One of the opening scenes of The City of Gold and Lead, in fact. The forward references aren't usually so self-conscious, but there are plenty more. There's plenty of material, too, about Switzerland and what will become the White Mountains base.
Christopher wrote this book in the aftermath of the BBC series, and there are one or two passages of ironic self-justification. Having been made to think about how the Tripods could possibly move, he now writes:
The three legs, swinging in succession, produced a motion which was a cross between lumbering and mincing.One of the minor characters is a brash, gullible schoolteacher called Hickey, given to unfair put-downs, who reminisces about the science-fiction of his youth and calls the first Tripod landings "absurd" and "a farce". This is a dig at Christopher's fellow British SF writer Brian Aldiss, who had been rather unkind to the basic assumptions of the trilogy when talking about the BBC Tripods on a television review programme. Aldiss thought it particularly ridiculous that, when hunting the heroes at night, the aliens "haven't even got infra-red". And here's Hickey:
Night had fallen by that time. And the Tripod switched on ordinary white light -- searchlight beams, you could say -- to find out what was happening beneath its feet. So it looks as though they don't even have infra-red!Christopher's rejoinder can be found some pages later, put into the mouth of the shy, stuttering Dr Monmouth, a trustworthy figure who doesn't underestimate the foe:
Scientific knowledge doesn't have to follow the pattern we're familiar with. The Incas had a superb road system, but didn't m-manage to invent the wheel. The fact that they use something as clumsy as a T-Tripod doesn't mean they might not be a long way ahead of us in studies of the m-mind and mental processes.By this time Hickey has fallen under Tripod influence and been taken away as a dangerous lunatic. And the moral of this story: be careful what you say about writers on television...