More reliable than baby due dates in the Lindo maternity wing of St. Mary's Hospital in London, are the die hard royal baby watchers outside. They're few, they're dedicated, and they're here rain or shine.
"We come as soon as they put the parking restrictions on," Maria Scott, 46, from Newcastle told ABC News, with a British flag tied around her shoulders like a cape. The parking restrictions come when authorities set up the press pen, and clear the street for motorcade access, Scott explained.
Kate's due date is rumored to be next week and they've been camping out for nine days already, just to be on the safe side.
"I've done it so long, I know the routine, the helicopters and the motorcade" said Terry Hutt, 83, from Camden Town, whose dashing Union Jack suit has been a mainstay at royal events for decades. "And I explain it to people who haven't done it before."
"As soon as I get that feeling," Hutt said, obviously excited at the thought, "butterflies, is what women call it, butterflies, that's it - I'll get on my feet and be ready."
But why camp out? One might ask.
Hutt, Scott, her daughter Amy Thompson and John Loughrey, 63, also donning a Union Jack suit, were all seated on a bench in the sun outside the hospital, next to some camping chairs and a tent draped with the British flag.
Scott said it's all about the electric atmosphere. Loughrey added that it was also about the celebration and the champagne. And for 83 year-old Hutt, well, it's tradition and team work.
"You've got to be here to experience it, seeing it on TV doesn't do it justice," Scott said, her flag now slightly off kilter. "It's just a wonderful feeling you get. The excitement is magical!"
The whole experience on the day of the birth doesn't last long. The Duke and Duchess emerge with their newest addition on the steps of the Lindo Wing, wave, say a few words to the crowd, and then they're off. That's it.
Did Amy Thompson ever think her mom was a bit nuts, honestly?
"No, no," Thompson says. "I've been brought up knowing everything about the family - and she's always been this way. Everyone has their thing and this is ours." Like her mother, she too, has become an ardent royal fan.
"It's indescribable. It means the world," Thompson adds.
The tight-knit group has done multiple events together and they say Kate even sent them breakfast the morning she gave birth to Charlotte. So, when do they think this new baby, the fifth in line for the throne, will arrive?
"Well, I was wrong," Hutt said. "I thought it would be last night and I got all packed up and ready to go."
Scott has her eyes on this weekend. "I think it's going to be on the 21st, the Queen's birthday," she said. Her daughter, Thompson and the others nod in agreement. "That would be lovely for the Queen. A wonderful birthday present."
The group is split on whether they think it will be a boy or a girl. And as for names, Philip Michael, Victoria, Elizabeth and Alice are all offered as viable options.
Hutt adds that he might like like them to name the baby after him or his wife. In the end though, he's just hoping for a healthy baby for the happy couple.
"It's going to be a beautiful day," Hutt said, adjusting his matching Union Jack printed fedora.
Like Thompson said, everyone has their thing.