Could this royal baby name beloved by Princess Diana be Prince Harry and Meghan Markle's pick for Baby Sussex?

The world is awaiting the arrival of Prince Harry and Meghan Markle's first baby.

Late last year the Duke and Duchess of Sussex revealed they were expecting their first bundle in late April or May. Now some news outlets are reporting Markle is over her due date.

The royal pair had previously shared they'd keep the birth of the newest member of the Royal Family private at first, stating they want to celebrate quietly as a family first. The decision has left many wondering if information about the baby, including its name, could be kept secret for a while.

Yet, some royal baby watchers seem certain they know what the name will be: one of Princess Diana's favourites.

Photo / Getty Images

A fresh round of bets has indicated an interesting choice. According to Ladbrokes, online betting has suddenly received a flurry of gambles for the name Allegra, forcing bookies to slash odds from 100/1 down to 20/1.

The Daily Express reports it was Diana's name of choice if she were to ever have a girl.

Since the odds opened last year, this move has been by far the biggest bookies have seen.

Spokesman for Ladbrokes Alex Apati told the Express: "It's probably the most bizarre eleventh-hour move we could've seen, but the money is coming in thick and fast for Allegra.

"We wouldn't be surprised to see the name right up there with the frontrunners by the time the birth gets announced."

After having two boys, Princess Diana reportedly longed for a daughter and wanted to call her Allegra.

It was alleged she shared this desire with a friend after hearing the name from Lady Annabel Goldsmith.

Photo / Getty

The source shared: "She thought it was a beautiful name."

The name belongs to Lady Sophia Pilkington's daughter, who is a cousin of Diana's friend, Lady Annabel Goldsmith.

The Daily Express says she liked the name because in Latin it means cheerful, lively and full of energy.

Despite the surge in bets, the name remains only the sixth most popular choice on the list of possibilities.

Monikers Grace and Diana are by far in the lead with odds at 6/1.

Should the Sussex's have a boy, the leading name is Arthur, with odds at 8/1.

Article first published on the NZ Herald and is republished here with permission.