Will and Kate left her parents' home in Bucklebury, England, on Friday and were headed in the direction of home, according to media reports.
This appears to scotch the notion that the royal baby would be born somewhere other than London -- which would have spoiled plans for the huge crowd of media camped outside St. Mary's Hospital.
The idea batted about by news outlets that the Duke and Duchess of Cambridge might pull a hospital switch, with the baby born in Reading instead of St. Mary's Hospital in west London, was a bit far-fetched.
The birthplace of the third in line for the throne has been set, and the protocol for the announcement of the birth has been outlined clearly. The plan is for Kate to give birth in the Lindo Wing of St. Mary's, where William was born to Prince Charles and Princess Diana in 1982.
But Prince William and his wife have been visiting the Bucklebury home of his in-laws, Michael and Carole Middleton, this week. And surprises do happen. Royal Berkshire Hospital in Reading is much closer to Bucklebury than St. Mary's, reportedly less than half an hour by car from the Middletons' home.
London's Telegraph quotes a royal source as saying "contingencies" were made for wherever the Duchess happened to be at the time she went into labor.
Meanwhile, back in London, media have been camped out at St. Mary's as the royal baby watch reaches fevered heights.
What does St. Mary's have over the Royal Berkshire? For one thing, Lindo Wing is private. Royal Berkshire has a public maternity ward, according to the Telegraph, which would have meant Kate and the highly anticipated newborn would rub elbows with commoner moms on her first night with the royal infant.
There was no immediate word on whether Kate and Will were headed for the hospital. The speculation is whirling minute by minute. London Times reporter David Brown tweeted that after the couple left Bucklebury, accompanied by armed police, the police returned to the Middleton home. "False alarm?" he wonders.
Armed police have returned to Duchess of Cambridge's family home in Bucklebury. Has Kate returned? False alarm? #RoyalBaby— David Brown (@DavidhBrown) July 19, 2013
The palace has promised an announcement will be made when the Duchess of Cambridge is admitted to the hospital in the early stages of labor. Until then, the crowd at St. Mary's remains on pins and needles.