The Emperor Waltz is long enough at 600 pages to be divided, in the old-fashioned way, into nine ‘books’. Each book has a date, sliding from 1922 to 1979 to next year to 203 ad to last month. This might suggest an overly systematic novel in the mode of David Mitchell’s Cloud Atlas or Eleanor Catton’s Booker Prize-winning breezeblock The Luminaries. But Hensher has always been a writer with a wandering, curious eye (on its most exhilarating display in 2011’s King of the Badgers), and The Emperor Waltz is a novel that, despite its superficial restraints, won’t sit still.

It begins in Weimar during the period of hyperinflation, a time of bold new ideas and failures of conscience, when the competing energies of Bauhaus and National Socialism are starting to make themselves known. Christian, a young art student, is seduced by the promise of the city; a Berlin poster has informed him that in Weimar ‘everything would alter… for the better’. Meanwhile Klee and Kandinsky sit in cafés, paying 200,000 marks for coffee. In a key passage, Christian, who impresses his teacher Klee with his forward-thinking approach to art, is confronted by the casual anti-Semitism of his landlady. He vows to move somewhere else, before quickly and shamefully changing his mind. It would be too much of an upheaval, after all. He ‘despises himself for his cowardice’, but he ‘already knew that that was the easiest path for his mind to take’.

Later, Duncan is setting up the first gay bookshop in 1970s London. He knows that he and his shop will be the target of spite, and so before the official opening he makes a point of regularly visiting all the other outlets on the road to foster goodwill. It is not until he spots a sandwich-maker — who has sold Duncan his lunch for weeks — spitting in his food before bringing it out with a smile that Duncan realises the futility of his politeness. The scene ends with a moment of tough resignation, as Duncan sees the struggle ahead: ‘In his wallet, he remembered, he had written down the number of a neighbourhood glazier, for the first time the shop window would be smashed with a thrown brick.’ After Christian’s lapse, Duncan’s courage is especially stark — the easy path is not for him — and Hensher is very good at emphasising these private shifts in thought against a vast background.

The novel has its oddities, however. A section entitled ‘Last Month’ is in the first person and appears to be at least partly autobiographical. The narrator is a diabetic novelist who finds himself in hospital with an infected foot. From his bed he observes the other patients, who are mewling and baying at the nurses, and for a few pages everything twists into a kind of despairing essay on friendship. ‘Was this all that human relations were?’, the narrator wonders. ‘To spread ideas that would benefit ourselves, to create a community in order to achieve what we wanted?’ The rest of the novel expands on that question, but this hospital interlude is a misstep, albeit an intriguing one.

Taken as a whole, though, The Emperor Waltz is rich and captivating, dizzy with memorable characters. And through it all is the mystery of Strauss’s own Emperor Waltz, which is poured out of distant open windows, selected on iPods, and played on the violin by Klee when he has put the paintbrush aside. Its meaning — and the novel’s — seems to change subtly with every repetition: it signals material transience; the constancy of art; the absurdity of grand notions; and the importance of rebellion.