A children's book has won the coveted Costa Book of the Year for only the second time in the award's history.
Frances Hardinge's supernatural tale The Lie Tree scooped the prize and was hailed by judges as a "fantastic story".
It is the first time a children's author has received the award in 14 years, after Philip Pullman last won for The Amber Spyglass in 2001.
Hardinge, who was visibly surprised when she took to the stage in central London, said she hoped it would bring children's literature into the spotlight.
"In the wider world, sometimes children's fiction is seen as a bit lightweight, in a way that I think is not deserved," she said.
"I would also see this as a recognition of the wonderful work that is being done out there throughout children's and young adults' fiction."
The Lie Tree saw off competition from debut novelist Andrew Michael Hurley's gothic horror story The Loney and author Kate Atkinson's A God In Ruins.
The Victorian detective novel follows the story of teenager Faith as she tries to uncover the details of her father's mysterious death.
The budding scientist finds a tree which, when fed with lies, bears fruit that acts as a gateway to understanding previously incomprehensible truths.
Her struggle for answers is set against the backdrop of a male-dominated Victorian society, a theme which Hardinge said she often explored in her stories.
"Female education is very important to me," she said. "I always have a problem with any convention, any prejudice that allows people to treat other people as inferior people.
"I don't write manifestos and then wrap a story around them, but while I am writing a story I do have a few bees in my bonnet and sometimes they come out for a little buzz."
It took the judging panel more than an hour and a half of deliberating before deciding The Lie Tree was the winner of the prestigious prize for 2015.
Judging panel chairman James Heneage said: "First and foremost, Frances Hardinge's The Lie Tree is a fantastic story.
"It is an important book, not only because it is a great narrative, with great characterisation, but because its central message of possibility for an intelligent girl who is out of touch for the age in which she lives is a very important one and, I would argue, relevant for today."
All five nominees for the best book award had already triumphed in separate Costa award categories, including first novel award, novel award, biography award, poetry award and children's book award.
The Costa Book Awards considers authors living in the UK and Ireland, with the winner of Book of the Year winning £30,000.