"I write only for fame," said Jane Austen in a letter to her sister Cassandra in 1796. Two centuries, six novels and countless spin-offs later, you feel that, whether she was being tongue-in-cheek or not, she might have thought twice before committing this thought to paper.

In this excellent book Claire Harman traces the emergence of the cult of Jane  from the early readers who admired the unique, natural style of her writing, to the legions of modern fans who are more familiar with the BBC's Pride and Prejudice than the book itself.

Austen's novels are so entrenched in our culture that, reading Jane's Fame, it comes as a surprise to realise that she wasn't always so adored. In fact she was out of print during the 1820s. More surprising (and amusing) still is Harman's description of Austen, aged 13, as a "jolly Samuel Beckett" writing skits for the amusement of her family.

But then it is our lack of knowledge about Austen that lets us mould her into our own ideal: paragon of virtue, chick-lit pioneer, or the rather more appealing "poker of whom everyone is afraid". Harman pinpoints Austen's canonisation  and her appropriation by the public  to the publication of a memoir by her nephew James in 1870. His portrayal of his aunt (gems include the observation that "the same hand which painted so exquisitely with the pen could work as delicately with the needle") kickstarted the sentimental image of "Divine Jane" that lingers to this day.

Meticulous research and a lively, engaging tone make Jane's Fame a diverting read, although there is little here that an Austen buff  and there are many of them  would not know already. The amount of information available about Austen's life is inversely proportionate to the number of books that have been written about her.

However, the fact that a new addition to the Austen oeuvre  the mash-up novel Pride and Prejudice and Zombies  has emerged since the hardback was published only proves Harman's point that, odd as it may seem, it is "impossible to imagine a time when she or her works will have delighted us enough".

Time was when you knew exactly when a biography was going to end. There'd be a proper death scene, with the family clustered around the four-poster prepared to pay their last respects as the biographical subject gasped or groaned their way into the next world. The reader watched from a tactful distance, hoping to catch some last, special words. As the last breath was drawn, the final page was turned. Life and biography reached the finishing line together.

Over the past couple of decades, however, biographical interest has refused to leave quietly along with the coffin. Instead, attention has become increasingly focused on the cultural afterlife of the subject. What happened in the 20 or 100 years following their death? Did their shade rise to giddy eminence, or plunge into obscurity? What difference did the discovery of new biographical material make to their reputation? And how did the subsequent editing and republication of key works change the shape of their textual legacy?

This increasing regard for the leftover bits of a life began in the academy, the consequence of critical theories that pulled attention away from a single reading of a subject's life and on to other versions (the author wasn't so much dead as protean and plural). Over the last 10 years, this multiple way of seeing has migrated into works aimed at a wider audience. In 2001, Lucasta Miller's The Brontë Myth proved that general readers as well as scholars were interested in the process by which three reclusive parson's daughters were turned into a cultural industry, complete with Haworth tea cosies and fudge. These days, any biography worth its salt will include a final chapter - very often the best thing in the book - that looks at the fate of its subject as it negotiates its own choppy cultural wake.

One biographical subject whose posthumous life has been spectacularly potent is Jane Austen, whose modest tally of six novels and 41 years has managed to spawn a hydra-headed global industry. Claire Harman, in her deft, elegant exploration of the cult of all things Austen, starts at the beginning, in Steventon parsonage. She reveals that, far from being a solitary secret scribbler, Jane was merely one of several Austens hungry for literary fame. James, her elder brother, was considered the writer in the family, although his sluggish poetry suggests that this had as much to do with his position as a golden older boy as with any talent. What's more, Jane was frank and unembarrassed about her unladylike pleasure in the material side of authorship. On selling the copyright of Pride and Prejudice, she wrote to her brother Frank that she had now earned £250, "which only makes me long for more".

This version of Jane - sharp, pushy, even a little unlikeable - lay dormant for decades, thanks to the smothering effects of a memoir published in 1869 by her nephew, the Rev James Austen-Leigh. According to his recollection, Aunt Jane was simply a merry little mouse who wrote in the slivers of time left between visiting the sick and teaching at Sunday school. The only occasion on which she exhibited a streak of pettishness was when she refused to have the door to the parlour oiled, as the squeak gave her time to tidy away her manuscript and compose her features into a bright, attentive smile. She was, in short, Saint Jane, an impeccably Protestant model of perfect womanhood.

This turning of Austen into a kind of universal aunt brought her a particular kind of admirer, often male. By the 1930s, David Cecil could quaver that anyone who didn't like her belonged to "a despised minority", comprised of the sort of people who "do not like sunshine or unselfishness". Kipling, meanwhile, wrote an unlikely short story in which officers and other ranks were bound together in the trenches by their abiding need to have a copy of Persuasion to hand. This strain of obsessive fandom naturally raised the eyebrows of those who stood slightly askance from middlebrow English culture: "What is all this about Jane Austen?" demanded a baffled Joseph Conrad, writing to HG Wells. "What is there in her?"

One of the technical difficulties for writers attempting this kind of "meta-biography" is that it can be hard to keep your audience with you. It's all very well eschewing chronological details of your subject's life in favour of a thematic analysis of their posthumous reputation, but what if readers need their memories jogging about what's what and who is who? Harman is lucky here in that several recent biographical films have seared the main events of Austen's life into the public consciousness. Thanks to Becoming Jane with Anne Hathaway and James McAvoy, we all know about Austen's early love affair with Tom Lefroy, even if we're vague on whether, as the film suggests, they really did almost elope. And a recent TV outing with Olivia Williams, Miss Austen Regrets, usefully introduced the real-life incident where Austen accepts a proposal of marriage from a wealthy neighbour, Harris Bigg-Wither, only to retract in panic just 12 hours later.

This profusion of biographical detail in the popular public domain absolves Harman from any requirement to rehash the basic outline of Austen's life. Instead she can be reasonably secure that her readers are able to keep up with her as she swerves between the Assembly Rooms and the blogosphere, or between Emma Thompson's oddly Forsterian delivery of her lines as Elinor in Sense and Sensibility and the fate of George, the disappearing disabled Austen brother. The result is a happy blend of critical insight and narrative bounce, making Jane's Fame a fine addition to the current trend for analysing posthumous lives.

 Kathryn Hughes's The Short Life and Long Times of Mrs Beeton is published by Harper Perennial. To order Jane's Fame for £18 with free UK p&p call Guardian book service on 0330 333 6846 or go to guardian.co.uk/bookshop