Not suitable for children: The dark side of JK Rowling

With the Potter days behind her, the author explains her obsession with killing characters

JK Rowling answers questions from fans at the Southbank Centre in London last night (Reuters)

As JK Rowling revealed the secrets of her hugely anticipated new novel, she told the adoring crowd something her earlier work had only hinted, that she was "obsessed" by death.

The Casual Vacancy, her first book aimed at adults, was released at 8am yesterday and the celebrated writer took to the stage of London's Queen Elizabeth Hall some 12 hours later.

They did not come in wizard's cowls or with lightning bolts felt-tipped on their heads. It was an audience that had grown up into their late teens and early 20s with Harry Potter. And a fair share of older fans as well. Rowling rarely appears in public, but held her poise when met by a standing ovation from large sections of the sell-out crowd of 900.

When asked about the adult subject matter in a book that starts with a death, the author said: "Death obsesses me. I can't understand why it doesn't obsess everybody." She later added that writing about death "has made me much less afraid of it".

Rowling said her view was coloured by her mother dying when the author was 25, and being part of an aged family "people did die a lot in my teens".

While the release of Rowling's first novel in five years had met with mixed reviews from the critics, there was nothing but adoration last night.

She was interviewed on stage by BBC journalist Mark Lawson, who kicked off by talking about the author's involvement with the Olympic Opening Ceremony, where she read a passage from Peter Pan. "It's one of the best things I've ever, ever done. I was proud to be part of it." After 15 years much of the Potter references are "white noise" but the sight of Voldemort rising up gave her "a full body chill. It was a big moment for me".

Rowling had flown from Edinburgh to London on the morning of the release, spending much of the day trying to avoid reading reviews. She has not always been comfortable in front of audiences of adults. Crime writer and friend Ian Rankin believes she is in her element "in a room of kids". And she was in her element last night with the questions from her young fans. One had flown in from Spain and got a hug from the author as he gave her a present.

She revealed that she would change "quite a few things" about the Potter series stylistically and a few plot points including giving Harry a map that proved "far too useful". She revealed Dumbledore as her favourite character from that series but had no regrets over killing off some of the most prominent characters.

The Casual Vacancy is set in the fictional town of Pagford, and follows the chaos that ensues after the death of a local parish councillor. It covers heroin addiction, prostitution, drug dealing and rape. "This isn't Harry, Ron and Hermione. These are very different teenagers; contemporary teenagers," she said. "I genuinely think that this is a humorous book. Some of that humour may be dark."

There is also a strong theme of social justice, about which Rowling herself feels very strongly. Residents of her childhood village of Tutshill in Gloucestershire denied that they had inspired the "snobby" attitudes of the middle class community. "It's life in a small town and everything that entails," she said. "Pagford is fictional."

The Independent's book editor said that despite being "slowed down by its fussy class geography and wheezing plot-motor, the novel builds into a vividly melodramatic climax".

Read all about it: JK Rowling on...

… e-books: "I was hesitant as I didn't know what they were."

… printed books: "I'll always love print. I can't read an iPad in the bath."

… the Harry Potter film casting: "They were all too good looking."

… the swearing in her book: "To depict Krystal without swearing would be ridiculous."

… the Harry Potter books: "There are things I would change – quite a few things."