Jane Austen may be too likable or lovable for her own good. Pride and Prejudice, which celebrates its 200th anniversary this year, was recently elected the nation's favourite novel, and Austen herself, adorably but overlusciously impersonated by Anne Hathaway in a 2007 biopic, is in danger of becoming everyone's favourite maiden aunt  witty, wise and benign despite her emotional disappointments and the restrictions of her life.

Her books, however, aren't frothy, frilly romcoms. With startling honesty they examine the friction between individuals and society, as well as exposing the secret collusion between love and property, and their ironic humour is often a reflex of despair. The first short chapter of Pride and Prejudice begins with a grand generalisation about the sexual allure of money and ends with an aphoristic character assassination that is hilarious because of its savagery.

I feared at first that Paula Byrne was a cosy, cooing Janeite. The Real Jane Austen deals with the fussy trivia of the novelist's life  lengths of lace, portraits on lockets, Indian pashminas, carriages  and I worried that this emphasis on her art of "minute observation" would diminish the force and daring of Austen's intellect, so evident when Pride and Prejudice expounds a "truth universally acknowledged" about the marriage market that no one else had ever dared to utter. Byrne's style can indeed be glutinously affectionate. She calls Austen's writing "lovely", extols the "wonderful" work of her fellow critics, snuggles up to her "sisterly circle" of fellow scholars in Oxford, and gives smoochy thanks to her "dearest husband" for his support. As Austen remarks with shrewd sarcasm in Mansfield Park, "the enthusiasm of a woman's love is beyond even a biographer's".

But this, fortunately, is not a biography. Rather it is a series of essays that show how humdrum household objects turn into emblems of Austen's character and evidence about her abiding concerns. A cocked hat is the excuse for an account of her brother's military career; some crimson velvet cushions recall the family's tenuous legal claim to a grand estate in Warwickshire that may have been the prototype for Mr Darcy's Pemberley; a barouche demonstrates how restlessly mobile and well-travelled Austen was; and an incriminating sample of lace prompts an excursion to describe the scandal of an aunt's trial for shoplifting.

Each of Byrne's associative loops ventures into a wider, more disruptive, often violent world, far from the sedate parsonages in which Austen lived. Best of all is her demonstration that the supposedly demure, sheltered novelist knew all about the profiteering imperialism that subsidised the leisure of her landed gentry. The Bertrams of Mansfield Park derive their wealth from a plantation in Antigua that is worked by slave labourers. Byrne suggests that their house ironically took its name from the abolitionist Lord Mansfield, whose adopted daughter had a "mulatto" companion, while Mrs Norris, the novel's malevolent meddler, could be Austen's waspish allusion to the slave trader Robert Norris. The crop that enriches the Bertrams is sugar, criticised at the time by Thomas Love Peacock as an "economically superfluous" and "physically pernicious" addition to the English diet; more shockingly, Byrne notices that Austen's father acted as an intermediary for cronies who traded in Indian opium. Was his library, a sanctuary for young Jane, purchased with laundered drug money?

Despite Byrne's attention to small things and their chintzy domestic pedigrees, she acknowledges that Austen looked askance at "conjugal and maternal affections". Her humour was decidedly racy: she admired the "cruelty and lust" of the mythical seducer Don Juan, joked about sodomy in the British navy by coupling "rears and vices", and in Pride and Prejudice she cheekily goads the runaway hoyden Lydia to ask if a maid can mend "a great slit in my worked muslin gown". Byrne rightly celebrates the "wild imagination" of Austen's juvenilia. In these skittish parodies, female libertines run amok, hijacking carriages and poisoning family members they dislike or biting off their fingers. The critic DW Harding once described Austen's comedy as an exercise in "regulated hatred'; here the hatred flagrantly disdains regulation. The same impudent fantasy provoked Austen to scribble marriage banns for herself and a variety of imaginary husbands in the register of her father's church.

Reinforcing the hypocrisy that glues society together, her family chose to praise her benevolence and sweet temper in the memorial plaque they installed in Winchester Cathedral while pointedly not referring to her novels. But it's odd to find Byrne insisting that Austen shared the "paternalistic Christian Toryism" of her clan. Her clergymen, such as Mr Collins in Pride and Prejudice or Mr Elton in Emma, are smarmy buffoons, and her Tory patriarchs, such as Sir Walter Elliot in Persuasion or Sir Thomas Bertram in Mansfield Park, are either vain ninnies or irresponsible absentees. It's Austen's boldness and her witty fury we respond to, not the piety her relatives posthumously attributed to her. Elizabeth Bennet, tramping through the mud to visit her ailing sister or cheeking the stuffy and snobbish Lady Catherine de Bourgh, has the unbridled instincts of a revolutionary, and she revenges herself on the aristocracy by marrying into its ranks.

The real Jane Austen, I think, was tougher and bolder than Byrne allows; she dared to defy the Prince Regent's patronising librarian, who offered her irrelevant professional advice along with a nastily devious invitation to stay alone at his London residence. Defending novels in Northanger Abbey, Austen declared that this was the literary form in which "the greatest powers of the mind" were exhibited, and her own achievement justifies that brazen claim. The novel is the book of consciousness and conscience, documenting the daily trials that, as Byrne says, "make us human". The stories Austen tells are always about prejudice overcome and proud, premature conclusions bruisingly revised. As she pointed out in a letter, we change every pore of our skin every seven years, so our thoughts and feelings surely alter at the same rate. Her books accordingly grow with us, and as we read and reread them they nudge us towards self-knowledge and the comprehension of others (as well as catering to our catty resentment of their existence); there is no better guide to the perils of society and the errors of judgment we make in exploring it.

Byrne's essays add up to a fine appraisal of the novelist's environment, truly Austenish in the way they burrow into a sequestered and often secretive private world. But small things like shawls and brooches come and go, fashionably ephemeral, whereas Austen is a classic and will be with us, I trust, for ever.