Yet there’s no denying that Dahl knew just what his juvenile readership liked: chocolate and witches and – to borrow some Gobblefunk, the language he invented for his Big Friendly Giant – the kind of filthsome, frightsome fare that makes kiddles squirm with gleeful revulsion. “To tell young readers that you can escape growing up by dying is dubious – drawn to the utmost an encouragement of suicide – and therefore both an ideological and an aesthetic flaw”. “This is a denial of growing up and mortality, but mortality is one of the aspects that makes us human”, Nikolajeva points out. He’d rather die with her, as his abbreviated rodent lifespan will guarantee.

And then there’s The Witches, whose child narrator, having been turned into a mouse, decides against returning to his human form because he dreads outliving his beloved grandmother. “Wonka is vegetarian and only eats healthy food, but he seduces children with sweets. Consider Charlie and the Chocolate Factory. But for all the funniness and dazzling linguistic acrobatics of his prose, she acknowledges that there are problems with his vision. “He is one of the most colourful and light-hearted children's writers”, she insists.

Maria Nikolajeva, professor of children's literature at the University of Cambridge, disputes the notion that there is any darkness in Dahl’s books for younger readers. Female characters tend to be either warm or wicked with nothing in between, while Revolting Rhymes brands Cinderella, that fairytale girl-next-door, “a dirty slut”. Charlie and the Chocolate Factory’s Oompa Loompas were originally depicted as small black pygmies with warlike cries. Teachers tend to be villainous, and even when benign, fail to impart any real wisdom. If he was a bigot, he was an equal-opportunities bigot. It’s easy to poke fun at such prissy parental responses but take a closer look at Dahl’s writing for children, and you’ll find something to offend almost everyone. In the decades since its publication, James and the Giant Peach has been lambasted for its racism (remember that bit where the Grasshopper declares “I’d rather be fried alive and eaten by a Mexican”?), profanity (‘ass’ appears at least three times), references to drugs and drink (all that snuff and whiskey), and sexual innuendo (a scene in which a spider licks her lips got readers in Wisconsin hot under the collar), not to mention its alleged promotion of disobedience and – wait for it – communism. The controversy has never gone away though. All told, his work has sold more than 200 million copies worldwide. Today, titles like Fantastic Mr Fox, The BFG and Matilda, which was released just two years before his death, aged 74, in 1990, regularly appear on lists of the most popular kids’ books ever.

The bfg illustrations