Charlotte has emerged as a late bookies' favourite name for the new royal princess, and it could leave the betting industry facing a seven-figure payout to punters.

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A late surge in bets for the name has pushed it into first place at 3/1 with Ladbrokes and Paddy Power, and level with Alice, the previous favourite, at the same odds with Coral.

Olivia has also made inroads in the betting market and is now being offered at around 4/1 or 5/1, while Victoria and Elizabeth remain popular.

Ladbrokes says if one of the fancied names is chosen, on top of many people winnning by betting on a princess rather than a prince, "the payout for the betting industry will be bumped up to a million pounds".

"We've never known a day of royal speculation like it. Charlotte is the new favourite, but Olivia is the name on the nation's lips," spokeswoman Jessica Bridge said.

Charlotte has a long royal pedigree. It is the feminine of Charles, the name of her grandfather the Prince of Wales, and was the name of George III's queen, portrayed by Helen Mirren in the 1994 film The Madness Of King George.

Likewise Alice was the name of the Duke of Edinburgh's mother and also a daughter of Queen Victoria.

Coral's John Hill said: "The betting suggests the most likely names are Alice and Charlotte, however, we've seen a huge gamble today for Olivia who was as big as 40-1 before the baby was born but is now as short as 4-1."

Bookies have estimated they already face a payout of more than STG500,000 ($A971,062) after heavy backing for a female royal. Ladbrokes said its payouts included STG15,000 to a man in Manchester having his first royal bet.

A Paddy Power spokesman said: "The punters are back caught in Charlotte's web, but it could still be Alice in Wonderland."