The name in question is Lily, which would appear to recall Her Majesty’s childhood nickname, Lillibet.
It was also the affectionate name by which her late husband, Prince Philip, used to call her.
The royal insider told OK! Magazine: “It would be a lovely nod to The Queen who was known as ‘Lillibet’ during her childhood but it’s also always been one of Harry’s favourite names.
“Back in 2019 when the Duchess was pregnant with Archie, she and Harry took part in a walkabout in Merseyside and someone in the crowd later revealed he’d asked her how she spells her daughter’s name – Lily.
“He took great interest in it.”
Other popular names with British punters include Diana at 5/1 and Elizabeth at 10/1.
The Duke and Duchess of Sussex announced their pregnancy on Valentine’s Day.
They broke the happy news by posting a black-and-white photograph of themselves in their garden on social media.