Outsider: Always Almost, Never Quite, By Brian Sewell

Brian Sewell admires the novels of Simon Raven and this, his own Bildungsroman, shares much with the gamey world of Alms For Oblivion as well as the elegance of the prose – the collision of high and low social worlds, an astonishing variety of sexual behaviour, an amused tolerance of human foible, an admiration of beauty in all its forms, a respect for intelligence and an underlying stoicism.

The tentative title may seem at odds with its author's apparent self-confidence. In the public mind Sewell, the London Evening Standard's art critic, is notorious for his trenchant dismissals of many contemporary artists and the curatorial establishment which promotes them. His voice, which keeps alive the Received Pronunciation of the 1930s, has become an objective correlative for unabashed elitism. Surely such superb assurance must stem from a patrician upbringing?

But no. Near the end of the book he explains that he wrote it to encourage others that "it is not the end of the world to be a bastard or a queer". For much of his life, both were shameful social disabilities. Sewell's mother was the daughter of a rich businessman, well-educated with a talent for the cello and violin. She had creative abilities and worked as apprentice-assistant to several minor artists. As old as the century, she had a good Twenties. A beautiful young woman with bohemian tendencies and a comfortable allowance, she had many affairs – including one with "the poorest Maharajah in India".

However, when she fell pregnant in 1930, as a Roman Catholic she refused an abortion and was cut off by her family. Sewell's early life in London was one of genteel poverty spent in ill-furnished rented rooms, from which mother and child would often do a midnight flit, leaving the rent unpaid. Sewell's mother only told him his father's identity when she was in her 80s: Philip Heseltine, better known under his pseudonym as composer Peter Warlock. He had committed suicide in a Chelsea basement before Sewell's birth.

Although his son is dismissive of his work, he is far from a negligible figure, with one masterpiece: the song-cycle The Curlew, a setting of poems by Yeats. Warlock's sexual and alcoholic excesses were legendary in the 1920s and these, combined with his powerful personality and intelligence, made him an irresistible model for novelists, including Aldous Huxley, DH Lawrence and Anthony Powell.

Sewell's bond with his mother was profound and claustrophobic. He slept in her bed every night until, when he was 11, she married Robert Sewell and a measure of financial stability entered their lives. She schooled him at home, took him to galleries and concerts, introduced him to literature. It was a lopsided education, culturally abundant, practically neglectful. When obliged to attend school by his stepfather, he failed to flourish.

Sexually, though, his time at Haberdashers' Aske's in Hampstead was riotous. There is a great deal of sex in the book, honestly and unpruriently recorded. This candour might once have cause scandal, but today the only shocking part is his rape in his late teens. After school he made a false start studying art history at the Courtauld, then about to enter a golden age of scholarship under the direction of Sir Anthony Blunt. He was too young, too undisciplined, too much in his mother's thrall.

His decision to do his National Service early was decisive. His two years in the army taught him discipline, self-reliance and loyalty. It also cured him of early ambitions to be a musician, artist or priest. Apron strings stretched, he returned to the Courtauld and immersed himself in the study of European art. He pays generous tribute to the debts he owes to his tutors and his fellow students.

The second half of the book is devoted to his eight years at the auctioneer Christie's, initially recruited to bring intellectual stiffening to its catalogues. It's a gripping portrait of an institution which mixed disinterested connoisseurship with brutal venality, ambition, greed and snobbery. A major source for important pictures was impecunious aristocrats, so social connections were paramount. A client's pictures could be "mislaid" by directors or damaged by the porters.

Sewell gained much experience at Christie's, but gave much more, particularly his creation of the prints and drawings department. But the promised directorship was always deferred. On learning that his advancement had been barred by a director who had said: "We've got one homosexual on the board, we don't need another," he decided to leave. Almost needless to say, the one gay director was an Old Etonian aristocrat.

Being a queer bastard of no provenance had trumped Sewell's talents and emphasised his position outside the magic circle of the Establishment. But though the book ends at this point, with its author jobless in his mid-30s, we see he has created a strong sense of self from unpromising beginnings.

He is confident in his abilities, loved and secure in many friendships and armed by experience. A second volume is in preparation.