A British mental health nurse has won the Costa Book Award.

The decision has taken the literary world by surprise. Nathan Filer beat four other writers from Britain to the title for his novel 'The Shock of the Fall' - which deals with mental illness. The award, formerly known as the Whitbread prize, considers works from British and Irish authors.

He says he always intended for it to be a simple tale:

Filer (33) drew on his own background for the book.

The judging panel praised the book as "astonishingly sure-footed" for a debut novel.

Filer spoke about the benefits of having more to his life than writing, adding that he was due to work a hospital shift this weekend.

He said: "I didn't set out to write about mental illness or schizophrenia, I set out to write about this character and his illness is one aspect of his character and there are many more than that".

It is the first time a debut novel has won the prestigious prize since Stef Penney's The Tenderness of Wolves in 2006.

Also in the running for this year's prize were Kate Atkinson's Life After Life, Lucy Hughes-Hallett for The Pike, an account of the life of Italian poet Gabriele D'Annunzio, and poet Michael Symmons Roberts for his collection Drysalter.

Chris Riddell also made the shortlist for his children's book Goth Girl And The Ghost Of A Mouse.