Ronald Searle was one of Britain's best-loved cartoonists, and Geoffrey Willans (if I remember correctly) a former teacher. If there is such a thing as a genius, then Willans and Searle together were one.
The Molesworth books purport to be instructional manuals by an English public schoolboy named Nigel Molesworth, about how to survive the school experience. From the day the first was published in 1953, they became a wild success, especially with schoolchildren. They are still in print and still eminently applicable (which says something both about the quality of the books, and about the nature of the British school system, which even at that point hadn't changed much in 400 years).
The wild misspelling that permeates them caused hysteria among parents, and their removal from many school libraries (the books, not the parents). Nevertheless, many phrases from them have since gone into the English lexicon, particularly "enuff said" and "as any fule kno".
The quartet consists of:
Down with Skool
How to be Topp
Whizz for Atomms
Back in the Jug Agane
and an omnibus edition,
The Compleet Molesworth, reprinted by Penguin as
Molesworth
These are considered absolute classics in the UK along with gems such as 1066 and all that. Whether they're intelligible in the US is another matter; but I didn't think Monty Python would be, and I was wrong about that...
The reviews here are sparse, I see, so look at Amazon UK for a fuller perspective.
I see also that the second-hand price of some of the individual volumes is becoming ludicrous, so best just to go straight for the Penguin. The original "Compleet Molesworth" was actually missing a small part of "Back in the Jug Agane" (which is why I bought the individual volumes), but I don't know about the Penguin.
I hope perhaps this has provided some context; now you can look at Amazon UK :-)
P.S. If you can't remember Britain in the 50's and need a cultural glossary, see my So You'd Like To... Guide.