The past, Julian Barnes once wrote, has a way of behaving like a piglet, greased up and let loose in a room. It makes a lot of noise. People make fools of themselves trying to capture it. Invariably, it slips away.

This is the very business of biography — “the most sheepish and constrained of the arts,” the English journalist and satirist Craig Brown writes in his new book, “Ninety-Nine Glimpses of Princess Margaret.” However, his study of the princess, the younger sister of Queen Elizabeth — and one of the 20th century’s great malcontents — is gloriously truant. Brown ignores all the starchy obligations of biography and adopts a form of his own to trap the past and ensnare the reader — even this reader, so determinedly indifferent to the royals. I ripped through the book with the avidity of Margaret attacking her morning vodka and orange juice.

Brown’s technique owes much to the experimental French writer Raymond Queneau and to Barnes’s”Flaubert’s Parrot.” He swoops at his subject from unexpected angles — it is a cubist portrait of the lady. One chapter tells Margaret’s story solely through the public notices that announced her birth in 1930, divorce in 1978 and death in 2002. Another enumerates her most famous rebukes. There is a list of possessions auctioned after her death — her pillboxes and playing cards, two silver-mounted ivory lemon-squeezers. One section riffs on the phrases coined in the year of her birth: “bail out,” “feel up,” “sick-making.” “Each of these three has something Margaret-ish about it,” Brown writes, “as do crooner and eye shadow and the adjective luxury.”

As a subject, the princess proves to be something she never was in life: obliging. Beautiful, bad-tempered, scandal-prone, she makes for unfailingly good copy, and heaps of it. “Everyone seems to have met her at least once or twice, even those who did their best to avoid her,” Brown writes. “She shows up without warning, popping her head around the door of every other memoir, biography and diary written in the second half of the 20th century” — usually to insult her hostess or use someone’s hand as an ashtray.

But, for a time, her charms were considerable. “Little hot looking pretty girl,” according to Ralph Ellison. Picasso desperately wanted to marry her. Peter Sellers would have settled for an affair. John Fowles publicly fantasized about abducting her and keeping her as a prisoner.

When the playwright Alan Bennett visited a friend, the television interviewer Russell Harty, on his deathbed, Harty requested the tracheotomy tube be removed. He just had to report that Margaret had inquired about his health — twice.

The princess could, her father said, “charm the pearl out of an oyster.” Her interests, however, ran more to sadistic parlor games (she makes an indelible appearance in Edward St. Aubyn’s Patrick Melrose novels). She was aflame with snobbery and, as she grew older, addicted to bullying and one-upmanship. She would boast about her royal status to her children, and insist lovers address her as Your Royal Highness. When needing a rest, she was known to commandeer the Queen Mother’s wheelchair.

“Disobedience is my joy,” she supposedly told Jean Cocteau. But it was more than that; it was her identity. It was the opinion of Gore Vidal, one of her more loyal friends, that since the queen was the source of national honor and duty, it fell to the princess to be the evil sister, the source of “creative malice.” (Of Vidal, the princess once said dryly: “The trouble with Gore is that he wants my sister’s job.”)

But, as Brown reveals, those cutting remarks and outrageous scenes were a form of bizarre achievement and autonomy in a life that was otherwise barren. Margaret had no education, no occupation, no formal role. From time to time she would preside over, say, the opening of a pumping station. Her relationships were chilly. She communicated with her mother by letter even when they lived one floor apart. Her marriage was a disaster. After the scandal of her love affair with an older, divorced man (a key story strand in Netflix’s “The Crown”), she married Antony Armstrong-Jones, a photographer who evinced a talent for cruelty all his own. He liked to leave little notes for her tucked into the book on her bedside table that said simply, “I hate you.” Other than her two children (oddly absent from the narrative), her most memorable accomplishment was gluing matchboxes to tumblers so she could light cigarettes without interrupting her drinking.

The wisdom of the book, and the artistry, is in how Brown subtly expands his lens from Margaret’s misbehavior — sometimes campy, sometimes desperate — to those who gawked at her, who huddled around her, pens poised over their diaries, hoping for the show she never denied them. History is not written by the victors, he reminds us, it is written by the writers, and this study becomes a scathing group portrait of a generation of carnivorous royal watchers.

“We don’t cut off the heads of royal ladies these days, but we do sacrifice them,” Hilary Mantel wrote in an essay on Kate Middleton. Without ever explicitly positioning Margaret for our pity, Brown reveals how we elevate in order to destroy. Who or what, in the final reckoning, is the true grotesque — the absurd, unhappy princess, those desperate to get close to her, or the system propping them all up?