As the author of the Harry Potter series – possibly the best-known book franchise in the world – it’s difficult for J.K Rowling to pen a new story without intense scrutiny being placed upon it, long before its release. So it should come as little surprise that she’s been writing under a pseudonym.

JK RowlingJ.K. Rowling at the premiere for the last ever Harry Potter movie

It should also come as no surprise that as soon as that pseudonym became obsolete, the book went from selling well to topping the Amazon charts. The Cuckoo's Calling had sold already 1,500 copies before The Sunday Times blew the lid off this thing, propelling it to the summit of Amazon’s book chart.

Rowling said she had "hoped to keep this secret a little longer" and described "being Robert Galbraith" as a "such a liberating experience". “It has been wonderful to publish without hype or expectation, and pure pleasure to get feedback under a different name," she said in a statement about that book, which has been called a “scintillating debut”. Rowling said her editor, David Shelley, had been "a true partner in crime".

J.K. RowlingJ.K. Rowling shot to prominence with the first Harry Potter book

A spokesman for Waterstones booksellers said: "This is the best act of literary deception since Stephen King was outed as Richard Bachman back in the 1980s." In a tweet, its Oxford Street branch joked: "SPECIAL OFFER: For today only, ALL of our books were written by Jk Rowling!" Spare a thought, though, for the person who turned down the novel, and now regrets not having a book by the world’s biggest author at her disposal. Kate Mills, fiction editor at Orion Books tweeted “So, I can now say that I turned down JK Rowling. I did read and say no to Cuckoo's Calling. Anyone else going to confess?" she tweeted.