The royal baby's due date of July 13 came and went, but a very pregnant Kate Middleton didn't check into the London hospital. So when is the baby's real due date?

Duchess of Cornwall and step-grandmother Camilla gave a clue at a public engagement in Cornwall with her husband, grandfather-to-be Prince Charles. She spoke spontaneously at the children's hospice they were visiting, USA Today reports.

"We are all just waiting by the telephone," she said to guests. "We are hopeful that by the end of the week he or she will be here."

But Kate Middleton and her husband Prince William weren't even in London this weekend,  where Kate is supposed to give birth in the Lindo Wing, the private wing of St. Mary's hospital, and where William was born 31 years ago. Despite the alleged July 13 due date falling on last Saturday, the Duchess of Cambridge visited her parents' estate in rural Bucklebury about 50 miles or an hour's drive outside London, the British media reported. According to HollywoodLife.com, Kate fled the unusual 90-degree heat wave flooding her Nottingham Cottage home to seek refuge in the cooler temperatures of her parents' house.

The Duke of Cambridge also was out of town this weekend and played polo games for a local charity with his brother, Prince Harry.

However, both are heading back to London and now Brits are waiting with bated breath for the announcement that Kate has gone into labor.

But they may have to wait for longer than they think. According to HollywoodLife.com and NBC, Kate's mother Carole Middleton reportedly told her friends that the baby will be a Leo, meaning the newborn would not arrive until at least July 23.

The palace's official statement about Kate's due date only says "mid-July." Kate herself mentioned July 13 to someone who asked during an engagement, USA Today reports.