How much money is too much money? In 2016, a 54-year-old former model divorced her Saudi billionaire husband. The court documents revealed the gaudy excesses of her lifestyle: a travel budget of £2.1 million a year, £1.02 million on clothing and jewellery, and enough funds for 52 new pairs of shoes. She asked for a settlement of more than £500 million. The judge awarded her £53 million.

This case is one of many dredged up in Serious Money, Caroline Knowles’s startling study of the lives of the super rich. Knowles, a sociologist, tramps through London like a later-day Charles Booth to examine the tidemarks wealth has left on the city and its surroundings. Walking, she believes, “exposes politics, like a sediment in the landscape”.

She begins in the City — the heart of London’s money-making machine — and moves outwards, through the neighbourhoods of Belgravia, Mayfair and Kensington to the plutocratic outposts of Richmond and Virginia Water in Surrey. Along the way, she encounters those who orbit the ultra-rich — from the doorman of The Dorchester hotel to a £300,000-a-year security manager — but rarely speaks to the nabobs themselves. As with Belgravia’s many empty properties, they are absent, even as they shape the city in their own image.

Knowles is alert to arresting details. Night managers at Mayfair’s most prestigious hotels keep a sharp eye out for single women ordering green tea — the favoured drink of sex workers, one tells her. The never-enough mantra of fancy hotels means staff go to ridiculous lengths to satisfy the rich and the glazed absurdity of their whims. One manager tells her he was dispatched to fetch a patch of lawn for a suite as the guest’s Pekingese only shat on real grass.

In another romping section, she investigates the mania for “super basements”. These disruptive renovations are as much a threat to neighbourly cohesion as they are to architectural stability. As with mega yachts, there are gradations of luxury — and jealousy. “Large” basements are two storeys deep; “mega” basements, meanwhile, sprawl at least three storeys below ground. Yet despite their grandiose capaciousness, they are still windowless and sunken: filled with gyms, cinema rooms and wine cellars, they still carry the suggestion of necropoli. Appropriately enough, builders sometimes leave earth movers entombed within these sites; on a multi-million pound project, it simply doesn’t pay to dig them out. These stratigraphic markers will attest to London’s extreme inequality long after their owners are gone.

The strongest chapter, though, is on the legacy of Grenfell Tower. Looming like a “partially decayed tooth” above the streets of North Kensington, its charred skeleton is, Knowles argues, symbolic of “an indelible moment of trauma and social witness”. The 2017 disaster — Britain’s deadliest since the Second World War, in which 71 residents died — occured in one of London’s most unequal boroughs. This tragedy was a rare moment where the “parallel tramlines of the rich and poor… momentarily crossed”. Some of Kensington’s residents gush to her about the area’s “mix”. By which, she argues, they mean its evident iniquity, demarcated along racial lines: “poverty and racism become neighborhood assets.” In the shadow of Grenfell, it’s hard to contest that excessive wealth distorts cities, corroding communities and fragmenting accountability.

Does the patriarchy bite particularly fiercely if you bank with Coutts?

Yet there are frustrations with her account. As the book progresses, the voicelessness of her subjects — the ultra rich — comes to seem an omission. Studying their lives, and haunting their habitats, Knowles’s approach feels curiously like of an archaeologist, or a safari guide: the rich appear as some long-vanished civilisation, an exotic species. The tendency to give her interviewees pseudonyms is a cute touch, but hurts her argument – observations blur into generalisations, insights are blunted by anonymity.

In fact, there are points at which her book seems curiously retrograde itself, especially in its discussion of the place of women in this world. The highest echelons of wealth are bluntly masculine: “Only 11% of the world’s billionaires and only 10% of millionaires are women”. Yet despite meeting some of those 10%, she is still tempted towards statements like “it’s as if the last decades of feminist action missed these streets completely”. Does the patriarchy bite particularly fiercely if you bank with Coutts? Are the lives of wealthy women uniquely burdened by misogyny? As neither, I’m not best placed to say. But I’m not sure Knowles really knows either.

She is unfortunate, too, in her timing. “Serious Money” ends with a coda on the Covid pandemic, speculating how it will reshape cities in its wake. But the war in Ukraine has forced a more pressing — and pointed — reckoning with mysterious foreign wealth. Knowles’s interactions with Russian expats are spry, ducking the Novichok and Jimmy Choo cliches. She meets one expat financier who tells her he pines for the privations of life in old USSR, even as he towels his hair dry, fresh from a workout in the gym of his £10 million Kensington pad. Another flamboyant philanthropist, having made his pile in the rat-eat-rat scramble after the collapse of the Soviet Union, says he is determined to now to do some good with his money — joyously, this involves a sustainable caviar business where the fish are tickled, not butchered, for their eggs. Such interactions confound easy headlines demonising foreign wealth. The reader wishes she spent more time in the company of these remarkable — and amusing — Russians.

The rich, Knowles writes, see the poor as “a bit like being in a zoo… like looking at a tiger in a sanctuary”. This describes her spirited, but somewhat surface-level, approach in “Serious Money” too. It is a wry primer to the extravagances of the super rich. But those behind the gilded bars remain elusive.