A historical novel about the life and loves of Anne Boleyn's sister has won the Parker Romantic Novel of the Year award.

The Other Boleyn Girl, written by Philippa Gregory, tells the true, but little known, story of Mary, sister of King Henry VIII's wife Anne.

The younger sibling bore two children by the King before he went on to marry the ambitious Anne.

The book beat the favourite, Joanne Harris' Five Quarters of the Orange, to the �10,000 first prize.

Joanne Harris was favourite to win

"When I first came across the story of Mary it was in footnotes and asides in history books," Ms Gregory said.

"Historians knew of her, but no-one had considered what a remarkable woman she must have been and what an extraordinary life she led."

The author's previous work includes Earthly Joys, Virgin Earth and A Respectable Trade, which was adapted by the BBC and starred Warren Clarke.

Oscar-nominee

Ms Gregory, who hails from Hartlepool, attended the prize-giving ceremony at London's Savoy Hotel.

Other contenders included Irish novelist Cathy Kelly for What She Wants and Susan Lewis for Silent Truths.

Joanne Harris had been put as favourite to win with William Hill giving her odds of 7-2.

Her first novel Chocolat was nominated for the Whitbread Prize in 2000 and went on to become an Oscar-nominated film, starring Juliet Binoche.

Ms Gregory was second favourite to win.

The judges were TV presenter Vanessa Feltz, broadcaster and journalist Liz Thomson and Robert Waddington, book-buyer for the supermarket Asda.