Briton Hilary Mantel has been declared the favourite to win the Man Booker Prize for Fiction after 95 per cent of all bets were on her novel alone, bookmakers said.
William Hill said it had "never seen a betting pattern like it" after a spate of bets highlighted Mantel's Wolf Hall, set during Henry VIII's reign, as "the only one in the running for the punters".
"It's almost like an unspoken psychic rumour has gone round that this will be Hilary Mantel's year," spokesman Graham Sharpe said, as the odds were cut from 12/1 to make it the clear 2/1 favourite.
"We'll lose a five figure sum if the support continues. It is as though a tip has gone around the literary world telling everyone that Mantel is a certainty.
"It's built up a head of steam very early on."
Mr Sharpe said the always-popular contest was notoriously difficult to call and betting does not usually heat up until the shortlist of contenders is announced in September.
But hundreds of people were placing bets of up to £50 on the 57-year-old from Glossop, Derbyshire, this year, just days after the long-list of 13 books was chosen from the 132 potential contenders, he said.
"Quite a lot of them (people placing the bets) are what we would describe as literary insiders," he said.
"Nobody quite seems to know why."
But he ruled out the notion of any foul play, saying: "It would be unusual for the judges to know who they were picking as the eventual winner already. I would be very, very surprised if the judges had already decided.
"It's not in the realms of crying foul or anything like that, it may be just a case of a lot of people deciding on the same one at the same time."
He added it was "very, very rare to see this type of gamble" and said it was "definitely the biggest Booker gamble since Life of Pi was backed as though defeat was out of the question a few years ago".
In 2002, bookmakers had to suspend betting on the outcome of the Booker prize after the award's official website accidentally displayed a dummy page naming Life of Pi's author Yann Martel as the winner.
Organisers insisted similar pages had been prepared for all of the shortlisted authors and Martel said that he had hoped it was a lucky omen before going on to win the prize.
Rival bookmaker Paddy Power also made Mantel's Wolf Hall the clear favourite, offering odds of 5/2.
The winner of the prize, which aims to recognise this year's best novel written by a citizen of the Commonwealth or the Republic of Ireland, will be revealed on Tuesday, October 6, at London's Guildhall.
William Hill's latest 2009 Man Booker Prize for Fiction odds are:
:: 2/1 Hilary Mantel - Wolf Hall;
:: 4/1 Colm Toibin - Brooklyn;
:: 4/1 Sarah Waters - The Little Stranger;
:: 6/1 JM Coetzee - Summertime;
:: 6/1 James Lever - Me Cheeta;
:: 10/1 AS Byatt - The Children's Book;
:: 12/1 William Trevor - Love and Summer;
:: 14/1 Ed O'Loughlin - Not Untrue & Not Unkind;
:: 14/1 Simon Mawer - The Glass Room;
:: 16/1 Adam Foulds - The Quickening Maze,
:: 16/1 Sarah Hall - How to Paint a Dead Man,
:: 16/1 Samantha Harvey - The Wilderness;
:: 16/1 James Scudamore - Heliopolis.