Why did she do it?

Why did the world's richest and most successful writer publish a book under another name? JK Rowling has returned to adult fiction with a detective novel – but her loyal readers would have had to turn detective to discover her authorship. She launched The Cuckoo's Calling under the pseudonym Robert Galbraith. Then, like most novelists, she waited to see whether it would catch a fair wind.

The book was well enough received. Fellow writers gave it generous quotes for the cover. Critics were complimentary, and so were readers in their reviews on Amazon.

Yet it sold modestly well, between 500 and 1500 copies in hardback depending on which report you read. Rowling, as Galbraith, shared the fate of many decent writers who enter the market with their souls filled with hope and watch while their bank accounts fill with little more than fresh air.

Ian Rankin put it well when he tweeted: "Debut novelist garnering good quotes from famed authors for the cover plus good reviews can expect to sell only a few hundred copies."

What a contrast to her first attempt at adult fiction. Publicity for The Casual Vacancy long preceded its publication. Advance orders ran into tens of thousands. On publication day its distinctive yellow cover dominated store fronts. It was a publishing event, that year's biggest. Other authors could only gaze on in envy as their efforts were overshadowed by Rowling, the publishing phenomenon. Who could have guessed that for her next venture she would choose to join them, if only for a few weeks?

Did she do it because she believes in fairness? Or is it because she wants to be valued on her merit and not her name? I'm sure it's that and I can't help admiring her. Think of the risk she was taking. Had the book not found a publisher or had it been panned by critics, her secret would have come out just the same. Rowling's involvement in anything is too newsworthy to stay secret for long. You can imagine the headlines.

I'm also interested that Rowling feels the need or desire to write. Her personal success was a real-life Cinderella story. Harry Potter transformed her from struggling single parent to a global personality of untold riches. Cinderella didn't go back to sweeping floors and shelling peas. Yet Rowling has never stopped writing.

Maybe it should instruct the rest of us. Why crave financial success when those who have it still want or need the satisfaction of work well done? I suppose it's the hallmark of a real writer, many of whom don't feel a day has been well spent if they haven't put pen to paper. What's important to them is to strive for improvement, to leave their chalk mark on the wall of talent. But with writing and books there is a further conundrum – and that is how do you know how high your mark is? Can you judge by sales? If so Dan Brown has hit the heights yet many avid readers would rather have their teeth pulled than open his covers. Ditto EL James and her extraordinary success with Fifty Shades of Grey.

At the other end of the scale you might start with the Booker short list. The best-selling author Robert Harris dismissed it as "evil" saying: "It encourages and fosters the difference between supposed 'literary' novels and perfectly good books." He castigated the literary establishment for heaping the most praise on the writers with fewest readers.

Rowling's attempt to go incognito through the publishing world like a queen traversing her kingdom disguised as a peasant has precedent. Ronnie Barker, the comedian and actor, submitted scripts under the name of Gerald Wiley. It was only when Wiley was summoned to a meeting and Barker turned up that his cover was blown. He did it because he wanted to be sure his jokes were funny and not accepted because of who he was. It's the same story with Rowling really.

Many writers have taken the same pseudonymous path, though not all for the same reason. The former poet laureate Cecil Day Lewis wrote 20 detective novels in the name of Nicholas Blake. Julian Barnes wrote about a bisexual police officer called Duffy under the nom de plume Dan Kavanagh. John Banville becomes Benjamin Black when he writes about Dublin pathologist Quirke. I heard Banville speak about the experience at the Aye Write! book festival in Glasgow. It was almost as though the different authorial name allowed him to write in a different style.

Perhaps that too affects Rowling. Does a new name allow her to leave her Harry Potter persona behind? Rowling isn't the only author with a well-known name and wondering how good she really is. In a Radio 4 interview to be broadcast this week the acclaimed writer Martin Amis talks of the "burden" of having Kingsley Amis as his father. He says it damaged his career.

Many struggling writers would envy him the instant recognition his father's name afforded him when he was starting out. But there are also the jibes. One critic described his meteoric rise as "rocket propelled".

In the back of Amis junior's mind there seems to be the question: would I have been so successful otherwise?

Amis senior was a meritocrat. I interviewed him when he was an old man and he told me about his club. It was a haunt of aristocrats, he told me, the ones who inherited titles as well as real aristocrats; people of talent.

Lottie Moggach, whose mother wrote The Best Exotic Marigold Hotel and many other books, has just published her first novel at the age of 36. She, too, must now face awkward questions. She was challenged on Woman's Hour about the advantages of her name. She freely acknowledged that growing up with an author demystified writing for her meant publishing was a familiar concept. Her book was still turned down by about six publishers.

And that I suppose is the saving grace of the uncertain and unregulated business of writing. It is a highly competitive world in which publishers dare not take the risk of publishing a dud – however appealing the name on the cover.

I can see why Rowling wanted The Cuckoo's Calling to be judged on its merits and not on the name of its author.

The Casual Vacancy sold because it was her first foray into adult novels. The reader response was muted. Now Rowling has the satisfaction of knowing her next book was good enough to be published and to be praised on its own merit. It's revealing that still matters to her.

What next? Since she has experienced the fate of those writers who, unlike her, did not hit the jackpot with their first publication, perhaps a future philanthropic venture will involve helping talented unknowns to better promote their works?

Now that would be a happy ever after ending, in the best storytelling tradition.