I don't mean to make Freud sound insecure and vile. Geordie Greig does a handy enough job of that in his new book, , a volume of prying and sabotage dressed up to resemble a book of love.

Freud, whose sexually loaded and densely impastoed portraits made him probably the most important British artist of the second half of the 20th century, died in 2011 at 88. He was intensely private. He granted few interviews and fended off at least one potential biographer, Greig reports, with the help of hired goons.

Until we have a proper biography, we have this book, written by the editor of , whom Freud admitted into his circle in the final years of his life, or at least far enough that they had breakfast together more than a handful of times.

Freud was old and feeble: he let his guard down. Bad move, old bean.

displays little feeling for Freud's work. Its history is patchy. Its tone is frequently what you'd get if you set celebrity writer Robin Leach loose at the Tate Modern.

There was "a Hollywood glamour to this brown-eyed temptress", we are told about one of Freud's early lovers. Freud and Caroline Blackwood, a Guinness heiress who would become his second wife, were "the most talked-about young lovers in London, with hidebound society agog". Young Freud and another temptress "canoodled".

is seldom boring, though, which is something. It is so force-fed with gossip and incident - brawling, rutting, gambling, cuckolding, exacting revenge - that Freud comes off as equal parts Cecil Beaton (society dandy) and Charles Bukowski (crusty bum). He was the original werewolf of London.

The lunatic details start early and keep coming. You turn each page the way a rat hits the little lever for another pellet of crack.

Who knew, for example, that Freud had an obsession "with a Johnny Cash song about swapping his brain with a chicken when the chicken was robbing banks"? (This unlistenable novelty is .) Or that he was caught naked dancing to , the Blondie song?

It's pretty well known that Freud gave Kate Moss a tramp stamp made up of two tiny swallows. (Freud supplied to Greig the unlikely detail that this went down in the back of a London cab.)

At 84, Freud "chucked breadsticks at a man who used flash to take a photograph in the Wolseley", a London restaurant. That fellow got off easy. A boxer when young, Freud loved to thump or head-butt his fellow Britons. One of his daughters recalls: "Dad used to hit taxi drivers and punched people in the street if he didn't like the look of them."

My favourite anecdote, melee division - it's about art dealer Jay Jopling - goes this way: "A dapper Old Etonian with signature 'Joe 90' glasses, Jopling had been having a quiet drink in Green Street, a dining club in Mayfair, when Lucian entered the room and attacked him. 'He kicked me on the shins, grabbed the girl I was talking to and walked out with her', he said."

The artist leapt on women throughout his life as if he were a flying squirrel in paint-flecked work boots. This volume goes long on his "serial sexual opportunism", his playing of "musical beds on a grand and anarchic scale". He married twice, and has many acknowledged and unacknowledged children, but always had overlapping lovers.

In Greig's account, he could be a sadist. "He became quite vicious, really hurt breasts and things," according to a lover. He liked anal sex with women, an acquaintance reports, because it was redolent of utter domination.

He liked his girls young - as young as 16, 17 or 18. He got them to his home by offering to paint them, often obtrusively naked. A 22-year-old managed to fend him off, and we read about an early painting session: "He started walking up and down and gesturing as he undid his belt." After a fight with one lover, he mailed her "a postcard with a crude drawing of her defecating". No dummy, she held onto it.

Freud painted with agonising slowness and required his models to be present for every brush stroke. Sessions could drag on for more than a year. After sitting for four months for a portrait, of her breast-feeding her son by Mick Jagger, model Jerry Hall was late for a session or two. Freud got his revenge, we read, by erasing her from the painting. He inserted a man in her place.

We do witness Freud commit acts of kindness and generosity in this well-illustrated book, but they are few and far between. In the stray details accumulated here he is mostly cruel, loutish, self-centred.

Freud probably was all of these things, some or most of the time. But there is never a sense of seeing him whole in . Greig turns him into a cartoon, a man without texture.

Almost our last image of Freud here, appropriately enough, is of him two years before death, during a photo-shoot, bopping a wild zebra on the nose. The animal bolted, and he clung to it. He was sent to the hospital with a groin strain, though many feared he'd been hurt much worse. It all worked out, sort of. Kate Moss showed up and gave the wicked genius "a cuddle in bed".