Mistakes will sometimes happen even in the best-run places. Pictured with this post, by way of proof, is a 1947 Penguin paperback of Graham Greene's The Lawless Roads, with the author's name misspelt on the spine.
It's still common to talk of 'typographical errors', or typos, but back in 1947 there really was such a thing: it meant a mistake made by compositors at the printer, rather than by editors or designers. Probably this was one; certainly that is what someone will have tried to tell Allen Lane. These days any mistakes are definitely our fault - in the case of the printed Spectator, indeed, they are usually my fault, as chief sub.
Which brings me to the other lesson of this book: how easily mistakes can be overlooked. I owned it for several years without ever seeing anything odd. Only last week, when I was filling up a new bookshelf, did the error jump out. Perhaps I'd never really read the spine before - I hope so.
Also, if you have read this far, and you have never previously come across Teresa Nielsen Hayden's Evil Spelling Test, go look. You're likely to enjoy it. For certain values of 'enjoy'.