How Wills-Kat kept everyone guessing about royal baby birth until the end

The Duke and Duchess of Cambridge were able to give the glaring eyes of media a slip when they entered the gates of the St Mary's Hospital shortly after 5.30 am on Monday.

The royal couple kept the birth of their baby boy a secret for more than four hours before announcing the news by email just before 8.30pm last night.

The world's media was camped outside the hospital for weeks in the hope of being the first to come out with the news of her hospital admission, but when William and Kate finally arrived, nobody apart from a freelance photographer, Jesal Parshotam, got the news. He tweeted the news at 5:55 am.

At 7.28am, the Palace confirmed officially that Kate was in labour and had been admitted.

Aside from one tweet, the final weeks of her pregnancy was a master class in stage management, during which the media was not able to photograph her or second-guess her plans, the Sydney Morning Herald reported.

The 31-year-old royal chose to spend almost all of last week with her parents at their Georgian manor house in Bucklebury, Berkshire, and was joined by her husband on Monday.

According to a source, in the middle of the afternoon on Friday, she and William slipped out, unnoticed, and returned to their London home at Kensington Palace, which is less than five minutes' drive from St Mary's hospital.

That meant that Kate's baby would be born in the Lindo Wing, rather than at the Royal Berkshire Hospital in Reading, which was 'plan B.'

The first sign that royal baby's birth was imminent came at 10pm on Sunday night, when royalty protection officers drove around the entrances of St Mary's in a 'dummy run,' which was witnessed by photogs and TV crews.

However, shortly after 5.30am, the Duke and Duchess came in a dark blue Ford Galaxy people carrier, rather than the Range Rovers, Land Rover Discoveries and Jaguars.

An ageing Saab 95 was used as the police back-up car to cause further confusion.

When Kate's staff began getting calls asking if the tweets were correct, they merely put them aside by saying that they wouldn't comment on speculation.

The photographers also missed Marcus Setchell, the Queen's former gynaecologist and the man who was chosen to supervise the birth, as he arrived at the hospital shortly after Kate, having been woken at his home in north London to be told that his services was needed.