POLYJUICE Potion. Tastes like goblin pee, according to Harry Potter, but it does the trick when you want to assume the form of another human being. Must be how JK Rowling did it then. How a glamorous, blonde behemoth of popular fiction morphed into a faceless former plainclothes military policeman scribbling his first effort.
But surely even she knew that it wears off very quickly – and that she would be no exception, despite inventing the stuff. We can read you like a book, Rowling, it seems. And not a very good one either.
Well, that's what Kate Mills, the publishing director of Orion thought when she turned down 'The Cuckoo's Calling' by Robert Galbraith, aka JK Rowling, history's best-selling author.
Mills said that she thought the tome was 'perfectly decent, yet quiet' and gave it a thanks, but no thanks. Yet it was apparently the assured skill of the penmanship that led the 'Sunday Times' to delve further into the backstory of the novel and eventually force Rowling to reveal herself.
And in the process, created a Potter-sized storm on a bookshelf, blowing this 'quiet' crime tale to the top of the charts within hours, boosting sales from 449 copies to, well, there probably aren't enough numbers for how high they'll eventually go.
All further proof that on the scale of importance in publishing nowadays, the one thing that's pretty close to the bottom is the actual story – the one that's in the published book, that is.
The story of the book, however – well, that's a different matter. In an increasingly difficult industry, what is becoming more vital to even getting your book on a bookshop shelf, never mind selling it once it's there, are three little letters that are more important than any writer will sweat out on to a page – that are even more important than the ability to write in the first place; U and S and P. Unique Selling Point.
I have a rough idea how this all works – my third novel will be published this autumn and pretty soon myself and my publisher will have to have the conversation whereby we try to think of stuff about me as a person, that's interesting enough to pique the curiosity of reviewers, to think of anything which might tickle the fancies of readers.
Because people don't judge books by their covers – it's tougher than that. Instead, they judge them by how interesting or well known the author is.
Fiction sells because it's penned by a politician with a penchant for durty bits, by purveyors of mummy porn, by how funny someone is on Twitter; because the author is already a celebrity, because of their family connections. Which isn't saying that these people aren't brilliant, talented authors and wholeheartedly deserve their popularity and every sale that they get.
But it is a reflection on the buying public who seem only willing to chance their pennies on a quick fix of the familiar or the famous.
Which is also fair enough with fewer pence in the pocket, but isn't it also important to dip an odd toe into the unknown?
Because if we don't give new stories a chance then how do we create potential future favourites? Undiscovered treasures – like JK Rowling, until we read her first story and loved it, despite the fact we hadn't a clue who she was.
And, once absorbed in that story, we didn't care because, ultimately, it doesn't matter.
Publishing is a tough world. Even for the likes of Rowling who is now always trying to live up to the standards of a writer's greatest critic – herself.
Maybe she invented Galbraith with good intention. Maybe she just wanted to tell a new story unencumbered by the millstone of prejudice that her previous success places around her neck.
Or maybe she's just a masochist who likes rejection letters.
Or maybe the entire Galbraith deception was a clever, failsafe and perfectly ethical ploy in which her unveiling was always intentional; her publishers assured that the big Ta-Daa would lead to an even bigger Ka-Ching.
Because USPs don't come much bigger than the name Rowling.
Now where's that Polyjuice Potion?