Gossip on its own wouldn’t have blown the identity of Robert Galbraith and revealed that the real author of a detective novel that was flumping along at the bottom of the sales figures was JK Rowling. Someone at Rowling’s legal firm told his wife’s best pal who the real writer was. The wife’s best friend tweeted it, thereby proving yet again that two people can keep a secret if one of them is dead.

All of that must have been pretty annoying for the woman who invented Harry Potter, but if the writer needs anger management right now, it’s probably because of all the knowing theories that have sprung up around why she wrote the detective story under a false name in the first place. First nudge/nudge theory? That the pseudonym was just a ploy. She really, really wanted to be found out as the author, and so she chose the name Robert Galbraith so that people would go “Galbraith. Galbraith? Who was the other author with that surname? Oh, yes of course, it was that economics guy. JK Galbraith. Gosh, isn’t that a coincidence? Double initial instead of a first name — just like yer wan who wrote the Harry Potter books. Bet it’s her, in disguise.”

Whenever a theory is as gratuitously elaborate as that one, you can figure it’s false. The reasons people put made-up names on their work amount to a handful, and the methodology likewise. Apologies for even mentioning myself in the same column as Rowling or Galbraith the Elder, but as a freelance journalist a few hundred years ago, I wrote environmental stuff under a male name because, back in those grim days before we eliminated sexism, editors wouldn’t take a feature on acid rain seriously unless it landed on their desk with a man’s name appended. So I fiddled around with the names of beloved nephews and developed several identities that way. As I got deeper into a position of identity pretence, I dug up my grandmother’s surname and used it. Just as well I didn’t use my grandfather’s, which was Colfer, or I’d have collided mid-flight, with Artemis Fowl, written by the immeasurably delightful Eoin Colfer. As it was, I got shouted at by another journalist who said I’d stolen her maiden name. I had to prove I had a legitimate claim on Geraghty.

I had so many false names, the postman was convinced a commune lived in our house. But that was his problem. Me, I was happy out. Nothing quite matches the freedom delivered by a pseudonym. It’s not just that you can write more freely; you can take up positions you disagree with. I once had three pieces in a one-page special in a broadsheet newspaper, all passionately fighting with each other on the same topic. Never much for fidelity in the ideas department, I believed absolutely in each in turn.

Writing under a false name, in the old days, required a bit of concentration. If I was being Geraldine Desmond, I had to forget that I had a husband and son, because Geraldine was single and getting around a bit. If I was being James Thornton, I had to change the typeface and send it from my sister’s address because the features editor who liked James couldn’t stick me, and so the connection between us had to be hidden.

Mostly, it worked. The only time it got awkward was when Kate Cruise O’Brien, the editor in my publishing house at the time, decided to bring out a collection of my short stories, which meant I had to go to the late David Marcus, who had published several of them under the name Mary Geraghty, and confess my duplicity. He thought me being so daunted by his fame that I would submit material under another name was very funny.

If you were prolific, in the old days, whether you were just a jobbing journalist or a book-writing author, you could invent yourself another persona, no problem, and prevent editors deciding that anyone who writes a lot of features or books quickly must be paying inadequate attention to the task. In fact, long intervals between features or books are often indicative of alcohol being consumed, rather than of slaving to produce filligreed sentences.

IN EVERY genre, you would find some writer who snuck work under the wire by pretending to be someone else. Jean Plaidy, an historical novelist of massive although, as it turned out, not abiding popularity, wrote a series of almost equally popular novels of a different kind under some name which now escapes me. Stephen King invented Richard Bachman for the same reason. Ed McBain, the American police procedural genius, wrote literary fiction, including The Blackboard Jungle, as Evan Hunter, and several other types of books including science fiction under names including Hunt Collins, Curt Cannon, Dean Hudson, Richard Marsten, Ezra Hannon and John Abbott. When I interviewed him before his death, he said he picked these names the same way he picked names for the characters in his books — by wandering along his bookshelves at home and picking a first name from the spine of one and a surname from the spine of another. But even Ed McBain wasn’t his real name. Although, if you’re going to write fast smart accounts of what goes on in the 87th Precinct, you don’t want to write them as Salvatore Albert Lombino, the moniker he actually got from his parents.

About ten years ago, a massive prejudice built up in newspapers favouring not only real names but photographs to match. This meant that unless you wanted to get into cross-dressing, wig-wearing disguises in the selfies you e-mailed to a paper, it was simpler to cave in and give your real name. The immediate and painful downside of which was that your income halved.

“Can’t have you appearing everywhere,” editors would say. “Bad for our brand.”

At around the same time, computer geeks started to develop technology that would observe and correlate patterns of word-use. As it grew more sophisticated, this technology revealed that every writer, good or bad, has a linguistic fingerprint distinctive to them and that nothing other than dementia substantially changes that fingerprint. Analysis of Irish Murdoch’s later work, compared with her earlier novels, established a significant loss in vocabulary long before her Alzheimer’s was diagnosed.

It was inevitable, once the rumours around “Robert Galbraith’s” novel The Cuckoo’s Calling started, that someone would decide to computer compare-and- contrast it with Rowling’s Potter series and so Patrick Juola, professor of computer science at Pittsburgh’s Duquesne University was commissioned by a newspaper to do precisely that. Once his work was done, so was Robert Galbraith. Financially, Rowling gains enormously because the book immediately began leaping off the shelves into the willing hands of purchasers because it now had referred brand association.

The sad thing, though, is that this writes an end to pseudonymous writing by energetic writers. Of course, they can be open and casual about their pseudonym, as is John Banville about his Benjamin Black pen name. But where’s the fun in that?