JK Rowling, the author of the Harry Potter books, secretly penned a crime novel which became a rave-review bestseller without readers realising she had written it.

The Cuckoo’s Calling, a story about the mysterious death of a model falling from a balcony which is probed by a war veteran turned private investigator, won universal praise from critics when it came out in April.

It was released by Sphere, part of the Little Brown publishing, and marked as a debut novel from ‘Robert Galbraith’.

Download the new Independent Premium app Sharing the full story, not just the headlines

Ms Rowling told the Sunday Times that she had hoped the true identity behind her pen name ‘Robert Galbraith’ would have been concealed for longer.

“Being Robert Galbraith has been such a liberating experience,” she said. “It has been wonderful to publish without hype and expectation and pure pleasure to get feedback under a different name.”

The book’s listing on Little Brown’s website confirms that Galbraith is a pseudonym. The biographical details say the writer spent seven “several years with the Royal Military Police”.

The 450 page novel has been likened to the works of prolific crime fiction writers Ruth Rendell and PD James.

Ms Rowling was under pressure after the worldwide success of the seven Harry Potter stories when she published her novel for an adult audience, The Casual Vacancy, last year.

It received a mixed critical reception, but claimed good sales and has been chosen for a BBC adaptation.