Harry Potter author JK Rowling wrote a secret fairytale manuscript on her 50th birthday party dress

HARRY Potter author JK Rowling has revealed she has written a “secret” fairytale, which she published in the most unlikely place.

JK Rowling has told CNN she has an unpublished fairytale manuscript. Picture: AFP/Angela Weiss

AUTHOR JK Rowling changed the world with her tales of a boy wizard named Harry Potter.

Now, the wildly popular author has revealed in a new interview that she has written yet another fairytale — but this one may never be published.

JK Rowling says she uses her husband Neil Murray’s surname in her private life. Picture: AP/Andrew Milligan, PA

Rowling, who famously wrote her first novel longhand in Edinburgh cafes, says that she scrawled the secret manuscript across her 50th birthday party dress.

She also added that the “book” now hangs in her closet.

“The theme of my 50th birthday — which I held at Halloween, even though that’s not really my birthday — was come as your own private nightmare,” Rowling told CNN. “And I went as a lost manuscript. And I wrote over a dress most of that book.”

However, the story may never hit bookstores.

“I don’t know whether it will ever be published, but it’s actually hanging in a wardrobe currently,” Rowling said.

Don't miss my exclusive interview with @jk_rowling on her children's charity @lumos. Plus a surprise for her fans @cnni Monday 8pmCET/2pmET pic.twitter.com/7vQKuBBxp3

— Christiane Amanpour (@camanpour) July 5, 2017

The British author, whose real name is Joanne, also opened up to CNN about why she continues to use a pen name after all these years.

“I quite like JK.,” she said, noting that her publisher recommended using her initials rather than her first name in an attempt to “disguise” her gender.

“I wouldn’t have chosen it for that reason ... but I was so grateful to be published, if they told me to call myself Rupert, I probably would have done [it] to be honest with you.”

JK Rowling has also written crime fiction under the pen name Robert Galbraith. Picture: Supplied

JK Rowling’s tales of the boy wizard Harry Potter became a global phenomenon. Picture: Supplied

Rowling has also written a series of crime novels under a second pen name, Robert Galbraith.

“I actually quiet like having a pen name, because I feel that’s — to an extent, that feels like an identity and then ... in [my] private life, I’m Jo Murray,” she told CNN, using the surname from her marriage to husband Neil Murray. “And it feels like quite a nice separation.”

JK Rowling, pictured with the cinematic stars of Harry Potter, Daniel Radcliffe, Emma Watson and Rupert Grint in 2011. Picture: AP Photo/Joel Ryan

Originally published as Harry Potter author JK Rowling wrote a secret fairytale manuscript on her 50th birthday party dress