I was more interested than is usually the case with things I see on Tumblr because, in it's original print run, the book was a complete mock-up of a Ladybird reader right down to the logo. Humour + Nostalgia opens wallets. (I'm working myself up into posting a rant about how nostalgia is probably a bad thing for society in general and another about my unrestrained loathing of stand-up comedians.)
The saga of Miriam Elia's 'journey' (I've come to loathe that word) in producing this wonderful book is chronicled here:
Artist's spoof Ladybird book provokes wrath of Penguin
My post-wallet opening journey begins here:
Anyway, basically (I loathe that word as well) the plot is Mummy takes Susan and John to a gallery and attempts to explain the concepts behind the works.
Buy the book because it's a hoot.