The EU referendum is probably going to be Britain’s biggest political betting event ever

GettyPrime Minister David Cameron (R) stands with London Mayor Boris Johnson as the Olympic cauldron is lit for the Paralympic Games in Trafalgar Square on August 24, 2012 in London, England. The London 2012 Paralympic Games open on August 29, 2012 for 12 days.

The EU referendum is on course to become the biggest betting market for a single political event ever, according to bookmakers Betfair.

The betting company said on Wednesday that several six figure sums have been being placed on bets relating to the June 23 referendum by customers —with the biggest individual trade so far coming in at £315,000.

If trading continues at this rate, Brexit betting is set to break Betfair’s record for political event trading. The largest trading volume the company has ever previously collected for a single political event was £40 million for the 2012 US Presidential election.

Naomi Totten, spokeswoman for Betfair said in a statement (emphasis ours): “The level of interest is unprecedented, it’s seen six-times more trading than the Scottish referendum at a similar point, and we’re seeing a steady stream of big punters requesting six-figure trades from our brokerage team.

She added: “As it stands, the market could eclipse Betfair’s [£40m] record for traded volume for a single political market. We’ve seen £8m matched to date and trading typically accelerates much closer to the event.”

Betfair has seen a huge flurry in EU referendum betting since the weekend and the company believes this is a result of US President Barack Obama’s recent intervention.

Both Betfair and Ladbrokes reported earlier this week that odds moved sharply in favour of Britain voting to remain after the President’s unusually strong comments about a Brexit. Obama said it could take up to a decade for Britain to strike new trade deals with the US if it were to pull out of the 28-nation bloc.

“Remain was already a strong favourite before Barack Obama’s visit,” Totten said. “But his comments sparked another wave of trading over the weekend with Remain backed as low as 1/3, which implies a 75% chance.”

A reason why the referendum has triggered so much betting activity could be how difficult predicting the final result is proving to be.

A YouGov poll published for The Times on Thursday, for example, gave Leave a one point lead (42 > 41%), but an average taken by What UK Thinks across polls published between the 12 th and 19th April indicated an eight point lead for Remain (54 > 46%).