One literary public relations executive needed.

Projects include high profile launches by a multi-millionaire author, arguably the most famous writer in the world, and creator of a book series which has sold in excess of 400 million copies worldwide. Skills include not sending out confidential memos to the nation's press in advance of any "highly secretive" events, along with obligatory crisis management.

Today's highly anticipated launch of Pottermore, an online "follow up" project to the Harry Potter books by JK Rowling, was stymied yesterday after it emerged that a public relations executive from StonehillSalt, a PR firm based in East Lothian, Scotland, had sent nearly a dozen national newspaper journalists, including reporters at The Independent, details of a confidential PR strategy document relating to the event, which has been shrouded in mystery for several weeks.

The document detailed what publicists should do in the eventuality that details of Pottermore leaked out ahead of time. Unfortunately for StonehillSalt, the document also contained details of the project.

A spokesperson for StonehillSalt claimed it was a "genuine mistake" and claimed it was an old working document, though that did not stop The Times, The Guardian, Metro, The Sun and The Atlantic running details of the alleged Pottermore project, to be announced today.

The project is reportedly related to a treasure hunt linking to an online game. The document said there were an unspecified number of "magic wands" hidden in Britain, the US, and potentially other countries, which ref-erred back to the website in question.

The PR company later claimed the story running was out of date, and today's announcement "would not relate to a treasure hunt" and said it was taking steps to get media outlets to retract their stories. Though, at the time of going to press, this still not happened, adding further to the widespread confusion surrounding the occasion.

"Much as we would like to say this is an elaborate stunt to create excitement, I am afraid it was a simple error," said Rebecca Salt, a spokesperson for Stonehill Salt. "The document is an old plan which is now out of date."

The information was contained in a Word file called "PR Timeline" attached at the bottom of standard invitations to today's press call at London's V&A. "As the number of people in the know about the project increases, so does the possibility of a leak," reads the document.

The Pottermore project is reportedly masterminded by Adam & Eve, a PR company that has previously conducted online-only treasure hunts using Google Maps.

The document, dated October 2010, continued: "We love the idea of a Daily Prophet wrap and would be happy to broker that deal with the paper of our choice, both in the UK and the US.

"It's such a fantastic story that we feel it should not be paid for but placed as unpaid editorial."

The project's overseers have secured their unpaid editorial – but possibly not for the reasons they had intended.