Author Hilary Spurling has said she is "gob-smacked" to have won the Whitbread Book of the Year for her biography Matisse, The Master.
By Caroline Briggs
BBC News entertainment reporter
The London-based writer scooped the prestigious £25,000 prize for the second volume of her illuminating biography about the artist Henri Matisse.
Spurling told the BBC News website she was amazed that she was only the fifth biographer to win the £25,000 award in the Whitbread's 21-year history.
And she admits she "didn't have an inkling" she would take the award ahead of fellow finalists novelist Ali Smith, first-time novelist Tash Aw, poet Christopher Logue and children's author Kate Thompson.
All five won separate Whitbread award categories earlier this month.
"I was astonished," Spurling said.
Ali Smith - The Accidental (Novel)
Tash Aw - The Harmony Silk Factory (First novel)
Hilary Spurling - Matisse The Master (Biography)
Christopher Logue - Cold Calls (Poetry)
Kate Thompson - The New Policeman (Children's book)
"To start with, biographers often don't win that prize - usually it is the novel - and this year it was a very good novel.
"But it was a really nice prize [to win] because all the contenders were very, very good books. The judges said there was a whisker between them."
Spurling, 65, said she hoped the judging panel felt the book, which she spent 15 years researching and writing, was a "page-tuner".
"Matisse was a drama-a-day man and had a very turbulent life so I wrote it that way. I hope they couldn't put it down.
"If you want people to read your book that is the first thing you have to aim for."
The former-Spectator literary editor began working on the biography in Russia in 1990, publishing the first volume, The Unknown Matisse, eight years later.
Matisse's family gave Spurling unprecedented access to the artist's private papers and letters for the painstaking research.
As Matisse's first biographer, Spurling said she had to go "back-to-basics" and strip away some of the myths that had built up around him.
"I was attempting to reverse the legend of Matisse, the legend that he was dull and stuffy and conventional and not very interesting," she said.
"That turned out to be complete nonsense."
"He was one of the most generous men imaginable, passionate in every relationship, and driven."
But despite finding the process of writing Matisse's life-story "endlessly fascinating", Spurling admits she would not have embarked on the epic project if she had known it would take so long.
"I could see it was going to take a long time, because I knew there was going to be a lot of first-hand research, but I thought perhaps seven years.
"Even that seemed like an eternity to me."
"There were so many times I thought 'I can't do this, it's impossible I don't see how anyone can do it'.
"In a sense it doesn't matter where you start. It is like a ball of string - you pull and you get an end. If you are trying to get into the heart of that ball of string you can start anywhere."
Spurling, whose previous biographies include novelist Ivy Compton-Burnett, said unravelling Matisse's story was a "series of shocks".
"[Matisse's] life would not have made sense if I didn't conjure up the world he lived in, which from the beginning to the end of his life, rejected his paintings.
"They treated him like a circus freak. He was rejected, dismissed and jeered at by the art establishment, critics, the public, dealers and sometimes by his fellow artist too.
"Matisse always hoped people would understand his paintings and they never did.
"He said it would take 50 years. Well he died in 1954, so we are those people and for the first time we do look without hang-ups we respond to them and understand them."
"We are the public he hoped for all his life."
Spurling, who says parting company with Matisse was a "great liberation", is already planning her next project.
"I've have a little list in the back of my diary for some time, but I haven't decided which.
"All I can say is that it will be something very short and completely different.
"I am going to write very short books from now on."