Ian McEwan’s shift, fully twenty years ago now, from the unique impassive weirdness of his first novels and story collections towards a sleek if never quite untroubling respectability won him legions of new readers, but it lost him some of his most passionate admirers. Or perhaps they remained admirers (if you’ve ever enjoyed the exactitude of his writing, the pure, head-clearing whiff of intelligence it gives off like an expensive eau de vie, you’ve likely continued to do so through thick and thin), just without the passion.

Partly, something seemed to happen to his perception of class, rather than to his politics. The bourgeoisie he’d thitherto observed with a pathologist’s dispassionate eye became, as in the work of some incarnadined Edwardian reactionary, the embodiment of virtue, the last, best hope for society. (Black Dogs, published in 1992, is more or less the final point where you feel the source and nature of such people’s authority being held up to any sort of overt analytical scrutiny.) His sense of what constituted an ending altered, too: where his earlier books didn’t end so much as just stop, in his later ones he seemed to discover a fondness for Shakespearean reconciliations and brisk summings-up of the kind that might almost have made the Telegraph obits page.

The books seemed to get at once more moralistic and more morally disputable. Briony Tallis shouldn’t, on the basis of the traits she exhibits in Atonement, have made a luminous career as a writer, certainly not in an age still blissfully ignorant of Rachel Cusk and Geoff Dyer. Henry Perowne shouldn’t have had the equanimity to operate on the yobbo who’d recently burst into his house in Saturday (and the NHS compliance department should have made damn sure he didn’t do so). Florence shouldn’t have been gifted a fuller afterlife than Edward in On Chesil Beach just because she played the violin and he ran a record shop. Michael Beard shouldn’t have got his comeuppance at the end of Solar (that sort never do, in life). The reader – this reader, anyway – was repeatedly left feeling like a dejected football fan, robbed in the dying minutes by a series of dubious refereeing decisions.

It was just possible to perceive a filament of satire running through all this, supercooled to just a whisker above absolute zero: all these characters triumphed or fell not through their own virtues or flaws, but simply because that’s the way society works. McEwan can’t not know, for instance, that there’s something not just laughable but grotesque in Perowne’s son Theo’s career as a blues guitarist, the music of unschooled African-Americans ‘mastered’ through what seems an almost entirely academic process. Perowne’s own lifesaving blade is held in a hand perhaps made firm by nothing more than narcissism. Poor Robbie in Atonement stands as a pretty fair emblem of the indignities meted out to the working class, too. But still: in or about 1992, reading McEwan stopped being a slightly queasy pleasure and has since felt more like a banal performative act of middle-classness, like scooping your pasta out of its Kilner jar and rustling up an Ottolenghi recipe.

If I now sound my sackbut and praise Nutshell as a return to form, it’s not because of that queasiness, although the easy acceptance of the morbid side of human relations that once led to McEwan being unkindly dubbed Gollum by critics is more in evidence here than it has been for a while. The book is an inventive reworking of Hamlet, narrated by a nearly full-term foetus, whose sense of the world, though partial in some ways (he doesn’t know what blue is), is in others remarkably full thanks to his mother’s nocturnal diet of podcasts and lashings of Radio 4: ‘She listens at random. I’ve heard it all. Maggot farming in Utah. Hiking across the Burren. Hitler’s last-chance offensive in the Ardennes. Sexual etiquette among the Yanomami. How Poggio Bracciolini rescued Lucretius from oblivion. The physics of tennis.’ He can recognise a Romanée-Conti even when it’s strained through a placenta. (In this he differs from his mother, whose tastes are more catholic: ‘If it’s cold and white I’ll like it.’)

Something is rotten in the run-down St John’s Wood town house our little prince is preparing to call home, though – and I’m not talking about the soft furnishings. Trudy – yes – his mother is trysting with uncle Claude. A plot is afoot: to diddle father John out of his ancestral home, which despite its poor condition still tips the scales at somewhere near the £7 million mark; and maybe something worse. Our narrator’s distaste for his mother’s shenanigans is partly based on practical considerations, which are observed with Gollumish glee: ‘Not everyone knows what it is to have your father’s rival’s penis inches from your nose’ is up there with ‘I felt myself shrinking inside his daughter’ from Black Dogs. But it’s also rooted in a strong sense of the fitness of things, which suggests that Trudy has not neglected to squeeze The Moral Maze into her listening schedule.

In this, our Hamilton Terrace Hamlet diverges from his most obvious recent avatar, Stewie Griffin in Family Guy. Like Stewie, though, he is – and this is perhaps the main reason why Nutshell was more of a pleasure to read than McEwan has been for some time – very funny. There’s a sense that the author feels relaxed about his material. The sciency bits don’t smell of the lamp as they did in Saturday and Solar. The many inconsistencies in what the baby does or doesn’t know, and what can and can’t transpire between him and his mother, aren’t allowed to trip the narrative up. The source text is kept in sight but McEwan only resorts to pastiche a couple of times, and then only when it’s telling, funny or both (‘These admirable radio talks and bulletins, the excellent podcasts that moved me, seem at best hot air, at worst a vaporous stench’). He lays out the unfolding intrigue – setbacks, set pieces, reversals, soliloquies, sharp-eyed gumshoes and all – with real glee. And the birth scene (spoiler alert) that heralds the end of the novel is done not just with an unflinching attention to detail, but with a real sense of fresh air, new life and even love, as the stifling radio play that our hero has been forced to sit through – a lurid but somehow mundane tale of house prices and nastiness in NW8 – falls away into the background and the sense-data of actual, lived life (‘The rest is chaos’) jostle in.