Column What's the worst thing you can say about Harry Potter?

How about claiming that spells are rather like computer programs? Or how about saying that Slytherin, the school house for all the bad guys, is a "cliche of fantasy"? Or maybe, pointing out that the name of Alecto (the female half of the brother-and-sister Death Eater gang in Half Blood Prince) is actually a name borrowed from one of the three Furies, the Eumenides of Greek mythology? David Langford says all these things in The End Of Harry Potter.

Yes, JK Rowling has opened the door, and the world's fans are working themselves into a frenzy about the Deathly Hallows. And (as Rowling remarked disapprovingly, "the first distant rumblings of the weirdness that usually precedes a Harry Potter publication can be heard on the horizon".

And if you go to any bookshop, UK or US, you'll find a table of Harry Potter books, all written by fans, enthusiasts and critics - and prominent among them, The End Of Harry Potter. Which, it seems, has been singled out for Rowling's most magisterial disapproval.

But why? Her official complaint was: she didn't want people to ruin the surprise by purchasing spoilers. A "spoiler" (outside motor racing circles) is a comment by someone who has read a book or watched a movie, which gives away the plot to someone who hasn't. And Rowling said: "I want the readers who have, in many instances, grown up with Harry, to embark on the last adventure with him without knowing where they are going."

Wow. You couldn't ask for a better endorsement of a book than an official recognition of its contents as a spoiler, by the only person who actually knows what the plot of Deathly Hallows will be. Which is a shame, because actually I don't think it is a spoiler. I did try to ask Langford himself this one but, although he hangs out in the SF community on CIX and answers such questions quickly, I probably asked this one too late at night...

Langford, obviously, is quite pleased with the encomium. "JK Rowling urging all her fans not to buy my book? Blimey," he commented in his 27 May entry on his "Ansible" site; "I never said people shouldn't buy hers..."

If Langford has tumbled to the truth of the plot of the final episode in book seven, you can be sure it isn't by espionage. It's pure, expert pedantry and frankly, if you want my sceptical opinion, it's too true for comfort.

But it's not the fact that it's a spoiler that is likely to have offended Rowling. It's the fact that the veteran "wit, slightly deaf person, raconteur, and finest swordsman in all of Christendom*" has really done the dirty on Harry Potter, and exposed the stage magician's finest tricks.

You can't easily claim that nobody has been able to uncover the mechanics of Rowling before. There are literally dozens of fan sites, and their analysis has been comprehensive. In amongst the daft, ill-informed or plain stupid comments there, there are several astute analyses - and Langford quotes several of these, attributing them to fans and fan-fic writers. But the tricky part is "in amongst" - the problem of any user-generated content site is that most of the users are, to put it gently, clueless. For every pearl, you have to eat many a dozen stale oysters.

No stale oysters here in The End of Harry Potter.

Instead, the gentlest of mockery, even when it's intended as praise. Take Potterist naming: I mean, come on. Are these names? or nicknames? or what? "Sirius Black, Harry's Godfather, gets an early mention in the first chapter of Philosopher's Stone, and we accept his forename as just another slightly odd wizard name..." says Langford, going on to point out that since Sirius is the name of the Dog-star and his name is Black, and his distinguishing characteristic is that he can turn himself into a Black Dog... well yeah, right.

And Rowling probably impressed a lot of people by naming the manic anti-Muggle activist Phineas Nigellus Black (Sirius's ancestor) but you can't hide esoteric mysteries from Langford. "...Seems to have taken his forename from the intolerant priest Phinehas in the Bible book Exodus." In that story, Phinehas punished a mixed-race relationship by the somewhat Gordian procedure of killing both partners to the relationship.

Another "coincidence" where the name anticipated the personality; and Langford lists all such coincidences. Professor Sprout, teacher of herbology? Oh, sure. And Professor Vector, teaching mathematics. And Lupin, a name which contains Lupus (Latin for wolf) whose first name, Remus, coincides with one of the two wolf-fed twins who founded Rome? - how amazing that he ended up being bitten by (and therefore becoming) a werewolf!

It's lovely, scholarly stuff. I can quite see why it won't seem like high praise to Rowling, but I learned a lot. And for an inveterate Spooneriser like myself, it's hard to believe that I never spotted "Sturm und Drang" in the school Durmstrang - but I didn't. And it's far from being the only enlightenment I got from the names chapter.

So much for the intellectual stuff (I hear you urge), but what about the plot?

If Langford hasn't dug out the plot, I'll eat my hat. He has picked up on every plotting device Rowling uses, and analyses them, showing how her mind works. And I'll tell you: if I wrote a seven book sequence which was such a mystery to so many people, I think I'd rather undress in the middle of the Albert Hall during a televised Prom concert, than have my secrets exposed quite so incisively.

But there's a teeny weeny problemette here. Langford has, I'll bet, written a book which in two months' time, he'll be able to pull out at dinner parties, and read aloud: "As I said in The end of Harry Potter," and go on to quote chapter and verse. Which is great, and clever and wonderful; but unfortunately, it's not the only thing he's said in that book. It's there, but so is everything else, and (as he keeps reminding us in the book) he hasn't seen the new book, and Rowling has not told him any secrets.

Example?

For example, take the chapter on foreshadowing - a technique, says Langford, which Rowling does very well:

"It's part of human nature to believe that important events cast long shadows backwards in time - that Tuesday's sinisterly dark and cloudy sky, or blood-red sunset, was an omen of the terrible murder on Wednesday. Perhaps the real world doesn't work that way, but books certainly do." And the chapter, "Shadows Before" illustrates several foreshadowing techniques. It's a list! Forked Tongue, Seeing Thoughts, The Mirror of Dreams, Spectres in General, Black Dog, Killing Grounds...14 ominous titles in all. Langford shows how throwaway incidents in the earlier books are as good as a programme guide (well, most programme guides are pants, but let that pass) in letting you know what's coming next. At least, with the benefit of hindsight.

"With the blinding clarity of hindsight, Dumbledore's death could be said to have been foreshadowed as long ago as in Philosopher's Stone. He has been playing an increasingly complex game against Voldemort and the Death Eaters - like a chess game for high stakes. In the magical obstacle-course of the book, Ron Weasley realises that the way to win on the enchanted chess board is to sacrifice himself, leaving Harry and Hermione to carry on to the next test."

And in that - perhaps - can we read a hint of where the last book is going?

At the end of book six, Dumbledore's end "can be interpreted in more than one way. If he is simply betrayed, then all along he's been deeply foolish to trust Severus Snape. Can we believe this about such a wise old mentor? It seems far more satisfying to imagine that in a final, chess-like gambit, he sacrificed himself so that others could go on and win the game for the Order of the Phoenix".

And, of course, the image of the Phoenix is another clue; one which Langford analyses, not in a superficial or trivial way, but with all his powers of erudition and all the data he's collected on all the Potter web sites, and in all the myriad SF books he's read, edited, or written, and from all the SF conventions he attended, lectured at, been GoH at...and then, as so often, Langford himself interrupts the flow and says that this is almost certainly not going to be the way it ends. Or maybe he doesn't! You are left with the certainty that if it is that way, he warned you. And if it doesn't, he hasn't misled you.

Don't read the book just to find out, six weeks early, what the final book says. Read the book because it will, without doubt, make the final book a far richer experience.

I'd say that I missed 90 per cent of the clues, foreshadowings, patterns, and other omens that Langford unfolds in this book. I simply didn't see them. I'll probably re-read some of the earlier books as a result.

Also, read this book to get the things you did notice put into better perspective. The orthodox Wizardly attitude to half-bloods; it's neatly done by Rowling, but Langford shows how neatly by spotting things you wouldn't have noticed, and tying them together with things you did, and making them all funnier.

Ah yes; also, read this for the laughs. I won't spoil them for you, but here's a clue: did you ever think that one possible ending of Deadly Hallows might be hauntingly familiar to the end of the Lord of the Rings?

"Only Kreacher knows the secret way into Voldemordor, which he learned from eavesdropping on past Death Eater gatherings in the Black house. Harry as the legal heir of Sirius Black, exerts his authority: Kreacher is forced to obey Harry's orders, and leads the way... Kreacher keeps muttering at the top of his voice (Oh, I LIKE that!) 'Kill the nassty Longbottom! Traitor to pure-bloods, yess, wicket traitor! Let the dark Lord eat his sssoul, my preciousss!' He also makes little gulping noises in his throat..."

It's truly not a spoiler. Even if one of the predictions Langford makes turns out to be spot on (I still think it will be) it won't spoil the telling of the story. The last Harry Potter book is not a simple, one-shot jack-in-the-box which, when opened, contains nothing except a spring. It's going to be a book; with people, suspense, conflict, fear, and - yes, of course, a surprise or two - and the final joy of revelation.

But the Langford book isn't just an exposure of the climax. It's something to tickle your fancy, to get your mind engaged, to start you considering the options.

Think of it as foreplay for the final penetration of the real mystery. Or, think of it - if you are not a fan of the kid in the specs - as a way of being able to talk knowledgeably about book seven, without having to read it. ®

* Endorsement by Terry Pratchett. Langford excels in blurb-collecting. How about "Ansible. Filled with wild rumour, suspect speculation, gross exaggeration, dirt and innuendo...unputdownable - Harry Harrison"?