Duchess of Cambridge
Britain's Catherine, Duchess of Cambridge, cuts a ribbon to release a bottle of champagne during the naming ceremony of the 'Royal Princess' cruise ship in Southampton, southern EnglandReuters

Kate Middleton's reported due date - 13 July - has come and gone even as the world is eagerly awaiting the arrival of the third in line to the throne. The royal family is tight-lipped about it but Kate's mom Carole Middleton has reportedly let the cat out of the bag by revealing the expected due date.

Kate's mom has reportedly told her friends that the much-awaited royal baby will be a Leo, suggesting that the baby will not arrive until at least 23 July, according to a report by NBC website.

It was earlier reported that Kate's due date was 13 July.

"Some of Kate and William's closest pals were at a barbecue hosted by a family friend of the Royals recently. They were all discussing the fact that Kate's baby is due to be born on July 13. Everyone was very excited," a friend of the couple had told The Daily Mail.

Even as the media is camping outside St. Mary's Hospital, where she is due to give birth any day, Kate reportedly left Kensington Palace for the Middleton family home in Bucklebury, Berkshire on Friday, suggesting that she is yet to go into labour.

Interestingly, the royal family has not revealed the due date though the Clarence House official website gave out a statement that the royal couple was expected a baby in July.

Kate will check into her suite in the Lindo Wing of St. Mary's Hospital, when she goes into labour.

The hype around the birth of the royal baby has been overwhelming, and the report by Centre for Retail Research (CRR) even claimed that it would boost British economy.

A new report by CRR said that the birth of Prince William and Kate's first child, who will be third in line to the throne, may boost retail sales by around £243 million (approximately $376) between 1 July and 31 August, 2013.

A total of £87 million is expected to be spent on festivities, £80 million on souvenirs and toys, and £76 million on books, DVDs and media.

"It is no great surprise that this type of feel good event provides retailers with a welcome boost, with consumer hype generating additional spending," said Professor Joshua Bamfield, director of CRR.