Image copyright Penguin

A fable about friendship and loss has beaten bestselling novels The Girl on the Train and Go Set a Watchman to be named Waterstones Book of the Year.

The Fox and the Star, by first-time author Coralie Bickford-Smith, is about a fox in a forest who loses his only friend, a star in the sky.

Bickford-Smith, who works as a senior book designer for Penguin, said she was "touched and honoured" to win.

"It's totally unexpected, it doesn't feel real," she said.

The designer-turned-author took a six-month sabbatical from work to write and illustrate the book.

Image copyright Penguin

"I wanted it to be a children's book but it's for adults as well," she told the BBC, citing inspiration William Blake's short poem Eternity and the graphic work of William Morris.

"It's about love, loss and learning to accept change. Everyone's been through loss. I lost my mum while I was at university, it resonated with that.

"But art has to be magical and mysterious, and I want people to project their own emotions onto it."

Bickford-Smith, whose design work includes cloth-bound editions of Penguin Classics, said her debut was "a blend of classical old book design with a modern twist".

"It celebrates the book as a physical object," she added.

Image copyright Penguin

The Fox and the Star triumphed over a shortlist which featured titles including The Girl on the Train by Paula Hawkins, Go Set a Watchman by Harper Lee, and classicist Mary Beard's SPQR.

The full shortlist was

SPQR by Mary Beard (Profile)

The Fox and the Star by Coralie Bickford-Smith (Particular Books)

My Brilliant Friend by Elena Ferrante (Europa Editions)

Reasons to Stay Alive by Matt Haig (Canongate)

The Girl on the Train by Paula Hawkins (Doubleday)

Go Set a Watchman by Harper Lee (William Heinemann)

The Shepherd's Life by James Rebanks (Allen Lane)

A Little Life by Hanya Yanagihara (Picador)

The shortlist was chosen from books nominated by Waterstones booksellers across the UK.

Last year's winner, The Miniaturist by Jessie Burton, saw an increase in sales of more than 1000% in Waterstones stores.

Waterstones boss James Daunt, who chaired the judging panel, described The Fox and the Star as "a book of great physical beauty and timeless quality, one that will surely join that very special group of classic tales that appeal equally to children and adults".