Prince William and his wife recently confirmed they are about to become first-time parents, but Catherine's former school friend, Jessica Hay, leaked the news a week before the official announcement.
She has now opened up about the royals' parenting plans, revealing they want to call their baby Diana, after William's late mother, if they have a girl, but the official decision won't be made until after the Duchess gives birth.
Hay tells Britain's Sunday Express newspaper, "Catherine's been saying, as per her mother's suggestion, that she wants to meet the baby first and then decide. If it's a girl, Victoria is a favourite and, funnily enough, Diana is a name that Catherine has always loved."
Hay goes on to reveal the pregnancy was a shock for the couple because they only started trying for a baby in September (12).
She adds, "They'd only been trying for a baby since the middle of September. It was amazing because they seem to have got pregnant almost on the first try."
A recent report from British bookmakers suggested Frances and John as the most likely names for the royal baby with odds of 9/1. Victoria is behind at 10/1, according to bosses a bookmakers William Hill, while Diana is an outsider at 12/1.
Diana, Princess of Wales was killed in a car accident in France in 1997.