Winning formula … EL James said she was overwhelmed to learn that Fifty Shades of Grey had been named Specsavers book of the year. Photograph: Philippa Cotton
The Booker judges went for Hilary Mantel, the Costa panel for Andrew Miller and the Orange team for Madeline Miller. But now the general public have spoken, and overwhelmingly voted for Fifty Shades of Grey as their book of 2012.
EL James's erotic fiction title took more than 75% of the public vote in the competition to be named the Specsavers book of the year. The 10 category winners of the National Book Awards were all up for the prize, including Clare Balding, winner of the autobiography prize, Mantel, named author of the year, Miranda Hart, winner of the non-fiction category, and Lee Child, who took the crime book of the year award.
Prize organisers said it was "no surprise" that Fifty Shades of Grey won the public vote, given its domination of charts and headlines since its release. To date, the novel has sold more than 6m copies in the UK, and is the country's bestselling book since records began.
James said learning of her win was "really quite overwhelming".
"Thank you so much for this wonderful award," said the author. "I am truly honoured. I have to thank the readers and the retailers for making Fifty Shades of Grey the success it has become."
Previous winners of the book of the year award include Caitlin Moran, for her memoir/manifesto How to Be a Woman, and David Nicholls for the romantic novel One Day.