Sex, drugs and village politics in Potter author's new novel

Pre-order sales of "The Casual Vacancy" have reportedly topped a million copies.

LONDON: Harry Potter author JK Rowling bids goodbye to the boy wizard on Thursday when she releases her first novel for adults, a gritty tale of poverty and politics in an idyllic English village.

With more than 450 million copies of the Potter books sold and fans feverishly excited about the British author's first major work since 2007, her new black comedy, titled "The Casual Vacancy", is already a guaranteed success.

Pre-order sales have reportedly topped a million copies and British booksellers expect it to be the best-selling fiction title of the year.

"It's one of the biggest releases of the 21st century," Philip Stone, charts editor at The Bookseller magazine, told AFP.

"I think 99.9 percent of us (in the industry) are predicting it will go straight to number one."

And as the world's first billionaire author, 47-year-old Rowling has the luxury of not needing to worry about paying the bills if her first foray into "grown-up" fiction is panned by the critics.

"I am the freest author in the world. I can do whatever the hell I like," she told Britain's Guardian newspaper.

"If everyone says, 'Well, that's shockingly bad -- back to wizards with you', then obviously I won't be throwing a party. But I will live."

Rowling's publisher Little, Brown has released some details of the plot, while a few more have emerged from the few journalists allowed advance access to the book, under tight security reminiscent of the height of Pottermania.

Set in the fictional village of Pagford in southwest England, the story opens with the death of a member of the local parish council.

Middle-class villagers soon begin plotting to fill the vacant seat with someone sympathetic to their cause -- ridding Pagford of its responsibility for the Fields, a squalid housing estate.

"We're a phenomenally snobby society," Rowling told the Guardian, "and it's such a rich seam. The middle class is so funny."

Tackling themes including heroin addiction, prostitution, single parenthood and adolescent lust, the book is a radical departure from the sanitised fantasy of her seven novels pitting teenage wizards against the evil Lord Voldemort.

Rowling said she had been itching to cover more adult topics.

"There are certain things you just don't do in fantasy," she told the New Yorker magazine. "You don't have sex near unicorns. It's an iron-clad rule. It's tacky."

Today, Joanne Rowling is a glamorous blonde with palatial homes in Edinburgh and London.

She is worth £560 million ($907 million, 703 million euros) according to the Sunday Times Rich List, with a business empire spanning eight blockbuster films, theme parks, toys and videogames.

But in the early 1990s she was battling depression and surviving on state handouts, struggling to raise her daughter alone as she wrote the first Potter novel in Edinburgh cafes.

Her experience of poverty and lone parenthood, following the breakdown of her short, disastrous marriage to a Portuguese journalist, was one influence on the plot of "The Casual Vacancy".

The book was also partly inspired by her youth, spent in villages similar to Pagford.

"This was very much me vividly remembering what it was like to be a teenager, and it wasn't a particularly happy time in my life," Rowling told the Guardian.

Her mother was diagnosed with multiple sclerosis when Rowling was 15 and she had a difficult relationship with her father -- the two have not spoken for around nine years.

These days, she can bring up her own three children -- she has two more with second husband Neil Murray, a doctor whom she married in 2001 -- in the utmost comfort.

But she insists that with money and fame, her problems have changed, rather than evaporated altogether.

"I am so grateful for what happened that this should not be taken in any way as a whine, but you don't expect the pressure of it," she told the Guardian.

Giving evidence to an inquiry into press ethics last November, she blasted the British press for invading her children's privacy.

Rowling is currently working on two more books for young children.

Where she goes from there may depend on her mode of transport -- Harry Potter was dreamed up on a train, while the idea for "The Casual Vacancy" struck her while she was on a plane.

"Obviously I need to be in some form of vehicle to have a decent idea," she has said.