Betting on two new Royal babies could now pay out at as little as 5/2 while one bookmaker, William Hill, has suspended bets entirely after reportedly receiving 200 in just over an hour.
The surge came on Monday night, prompting William Hill to slash the odds on Royal twins from 20/1 to 9/1 before suspending bets entirely.
William Hill spokesman Rupert Adams said: ‘We have had a load of unexpected bets including a large number of new accounts.
‘With any other market I would say that people know.’
At the same time Coral had a surge of bets which prompted it to slash its odds – which were 20/1 just a few weeks ago – from 10/1 to 8/1.
Ladbrokes was also offering odds of 8/1 last night while Paddy Power had cut its offer to 5/2.
Coral claims it was the first bookmaker to cut the odds on Royal twins last month after one punter placed a £1,000 bet at 20/1. Even after the odds were halved to 10/1, a psychic from Hampshire placed a £500 bet on the double birth.
Coral spokesman Nicola McGeady said yesterday: ‘Since Will and Kate announced their news, all the big money has come for twins.
‘With the gamble picking up pace overnight, we fear someone knows something we don’t.’
Punters have made a string of special wagers since it emerged last month the Duchess of Cambridge was pregnant with her second child.
Elizabeth is the bookies’ favourite for the baby’s name if it is a girl, or James if it is a boy – and David Cameron and Boris Johnson are 50/1 outsiders to be godparents.
The odds on history-making Royal triplets, meanwhile, remain steadfastly remote at 100/1.
And betters may be wary, as odds were also slashed on the prospect of Royal twins during the Duchess’s first pregnancy.
Experts said her age and the severity of her morning sickness raised the chances of a double birth – but when Prince George was born weighing 8lbs 6oz, he had no brothers or sisters to play with.
The last Royal twins in what are now the British Isles came in the 15th Century, when James I of Scotland’s wife Queen Joan gave birth to two boys.
Alexander was named heir to the throne but died as a child, and after his father was killed it was left to his twin brother James to assume the title of King James II of Scotland.
But there have been Royal twins elsewhere in the world since – including Josephine and Vincent, who were born to Danish Crown Princess Mary and Crown Prince Frederik in 2011.