27/09/2012 18:21 BST

J K Rowling The Casual Vacancy: Harry Potter Author Has Book For Children 'Half-Written'

Harry Potter author JK Rowling said she stopped writing another children's book in order to pen her first work for adults.

Bookshops opened their doors early today for readers to get their hands on The Casual Vacancy, the author's first full-length book in five years, which is expected to fly off the shelves following her record-breaking Harry Potter series.

The best-selling writer said the book - which opens with the death of a parish councillor Barry Fairbrother - reflected her obsession with the subject.

J K Rowling has spoken about her book 'The Casual Vacancy'

Rowling, who described herself as "death obsessed", said: "I can't really understand why it doesn't obsess everyone. I think it does really.

"Why does it obsess me? I don't know. The easy answer is my mother died when I was 25, She was only 45. That was clearly a formative experience".

She said writing about death so much had made her "less afraid of it" but said she was "frightened" of leaving her children.

She said: "Things lose their mystique when you think about them a lot, when you consider them a lot."

Rowling read from the new novel, published today, and answered questions at an event for 900 fans at London's Southbank Centre tonight.

She said she got the idea for the book, based around a local council election, while on a promotional tour for Harry Potter in the United States.

She said: "At that point I had another book for children half-written, which is still half-written, and I had a couple of other ideas, then I had this idea."

Rowling said it was easy to find her "voice" for adults because she had tried to write for them before,

She said: "I don't want to give the impression I'm sitting on a huge mountain of manuscripts but before Potter I did write for adults."

The plot revolves around the space left on the parish council by Fairbrother's early death.

Rowling said she was annoyed when she realised she had named him Barry - which rhymes with the first name of her young wizard.

She said: "I swear to you, this is the thing, it's so obvious to you and it's not at all obvious to me.

"I was going to call him Kevin and now I wish I had."

The book has been published to mixed reviews, with the Daily Mirror describing it as "a complete joy to read" and an "entertaining evocation of British society today".

The Daily Mail's Jan Moir was less impressed, describing the novel as a "relentless socialist manifesto masquerading as literature".

She said the book was "overlong" and "bogged down with detail", adding: "But then, who would dare to edit the most successful author in the world?"

Rowling told fans there were "quite a few things" she would change in the Harry Potter books and said the actors who played the three main characters were "all too good-looking".

She also said she regretted the secrecy over today's publication but said the internet and threat of piracy had forced her publisher's hand.

Rowling, 47, has amassed a fortune estimated to be around £620 million from her seven Harry Potter books for children and all the spin-off rights.

She recently said she left "the door ajar" for a return to the world of Harry Potter but there would be no more books about the young wizard.

"There's only one reason to write now: for me," she told the BBC.