New Baby Details Emerge as Royals Celebrate Prince William's Birthday Britain's prince william, celebrating his 31st birthday today. And we're learning more about what will happen when kate and williams' baby arrive soon. We have pictures of william when he was a baby. We're in the final weeks until the world's soon-to-be most famous baby is born. Duchess kate is officially on maternity leave. I'm sure they will carve out some time to celebrate prince william's birthday today. Happy birthday, prince william. The royal father-to-be, turns 31 today, just days after duchess kate made her last official appearance before maternity The queen also keeping up with appearances, celebrating a big day at the races. Look at the delight there. The sheer joy. Reporter: Brand-new images of a beaming queen elizabeth on thursday, as she became the first reigning monarch to win the ascot gold cup, a race the 87-year-old hased every year since 1922 as seen her on the monarchy's official facebook page. Despite how up-to-date the queen laz become, some traditions will remain, well, just that. One month before the most famous baby in the world is due to arrive, we've learned just how the birth will be revealed. The new baby's birth will take place in the hospital, almost certainly. But paddington railway station. And there, the royal doctor having seen the birth, will certify it on a piece of heavy note paper, brought specially from buckingham palace. That piece of paper will be placed here on a notice board, on that easel, there. Reporter: On that note, the most sought-after details the world has been waiting for. The time of birth, the weight, and the big reveal, the future king or the possibility of a future queen. I think most people in britain are really hoping it will be a girl. And that this new baby will take advantage of the new law. The first-born baby is a girl, that baby will become the heir and the future monarch. Reporter: William and kate have confirmed they won't find out the baby's sex in advance. Though kate has said she'd like a boy first. And william said he is hoping for a daughter. An interesting nugget a surname or last name will not necessarily be required. The royal baby will hold the title of his royal highness prince or his royal highness princess. If catherine and william want their baby to have a last name. There's windsor, wales or cambridge. We know it all now. We know it all. Well prepared. Or ith.