BREXIT BETTING: The biggest single bet on Remain is 10 times larger than the biggest bet on a Brexit

The biggest single bet placed on Remain was 10 times larger than the biggest bet on Leave, according to bookmaker William Hill.

A woman in London placed the biggest Remain bet at £100,000 ($147,750) with odds of 2/5, which would yield a £40,000 profit if the gamble comes good.

Meanwhile, another London woman placed £10,000 ($14,750) on a Leave vote at odds of 11/4, potentially making a profit of £27,500. Remarkably, it was her first ever bet.

As a record voting turnout is expected, William Hill spokesman Graham Sharpe said the amount of betting for a political event had been unprecedented:

"We have been taking bets on the outcome of an EU Referendum since January 20, 2013," he said, "when a customer from Jersey staked £20 on Leave. At that time the odds were 8/11 (57%) 'Remain, Evens, (50%) 'Leave', the closest they have ever been. Now there is some £20 million riding on the outcome with fixed odds bookmakers."

And it is not just Brits voting on Brexit. William Hill says it has taken bets from clients in dozens of countries worldwide, "including Andorra, Austria, Canada, Finland, Holland, Japan, Malta, Russia, Sweden, Switzerland, Ukraine."

Odds for a Leave vote have tumbled in the past few days, with Ladbrokes now pegging Brexit's chances at just 24% and William Hill at 25%.

Here are the current odds on a Brexit from the major bookmakers on the morning of the vote:

• William Hill - 10/3
• Ladbrokes - 3/1
• Coral - 11/4
• Paddy Power - 3/1
• Betfred - 3/1
• Skybet - 3/1
• Betfair - 10/3

A voting poll from SurveyMonkey - the group that correctly predicted the last General Election - gave Remain a slight edge, but the outcome of the referendum is still far too close to call: