Eva Gabrielsson on Stieg & Me

 "Is this place falling apart?" asked Eva Gabrielsson, as the wind rattles the tents at Hay Festival.

She was there to discuss her book Stieg & Me, her account of her 30-year relationship with her companion Stieg Larsson, the author of the mega-selling Millennium Trilogy, who died in 2004.

She revealed the trilogy - The Girl With the Dragon Tattoo, The Girl Who PLayed with Fire and The Girl Who Kicked the Hornets' Nest -  "wasn't really a serious project from the start" and was "mainly a private entertainment. [It wasn't] planned for publishing".

The novel's anti-heroine Lisbeth Salander [pictured above in the David Fincher film version] was created by chance, she said. The stories were meant to follow the character of campaigning journalist, Mikael Blomkvist, but "he needed something that was his opposite counterpart".

The first novel was famously originally titled Män som hatar kvinnor (Men Who Hate Women) and Gabrielson revealed that the Swedish publisher had not wanted to use the title: "Steig refused - he would not have agreed the title change in English either [if he had lived]" . Larsson died nine months before the book was published in Sweden.

On the litany of biographies about the author, she said: "The majority of biographies about [us] would not have appeared at all if he had lived - no one would have had the nerve to write them".

She also expressed a fear about other writers continuing the Millennium titles. "I'm really afraid of ghostwriters - who wants to see 20 Millennium books?"

While describing the Tattoo books as a "business", Gabrielsson said she found the books' massive success - more than 50 million copies have been sold - as "baffling": "nobody could have expected this kind of global success not even the publisher. It's totally out of the blue."

Stieg & Me by Eva Gabrielsson is published by Orion