I'm Terry's UK publisher and thought I should answer this query.
These copies with the missing "A" on the spine were part of an early batch of a reprint which were never on sale due to the typo (which was spotted as soon as the first copies arrived in the office). Rather than junk the batch, we decided not to waste them (there’s nothing wrong with the inside pages) and used them as free gift to schools to introduce new readers to Terry’s books and the Discworld.
So those copies were intended to be in the hands of a young reader and be passed around in school. I’d always intended to offer a free lollipop, gold star for spelling, or something suitable for the intended age-group in the event that any eagle-eyed kid spotted the typo and took the trouble to write in. I could offer a lollipop in this case if the poster is still in full-time primary or secondary education...
Would prefer to see these copies in the hands of kids, of course.
Phillipa: Congratulations young reader! You are a Winner! For correctly spotting the misprint on the book you get a lollipop!
Young Reader: A lollipop! A lollipop?!!!????? I note that a highly collectable world famous contemporary writer's publishing house has issued a highly acclaimed prize winning book with an obvious and indeed may I say highly COLLECTABLE and valuable dust jacket on it... I take the time and effort to alert said publishing house to the error and I get a LOLLIPOP! William old chap! Crank up the computer, get the camera and pull up ebay...... We WILL have new shoes for Christmas dammit!
Just keep swimming... just keep swimming.. just keep swimming....