People celebrate the news that Catherine, Duchess of Cambridge, gave birth Monday to a baby boy. (Isabel Infantes/AFP/Getty Images)

Catherine, Duchess of Cambridge, gave birth to a baby boy Monday morning, sparking an outpouring of joy in Britain. The news was warmly welcomed by the many royal superfans who had spent weeks camping outside the doors of St. Mary's Hospital in London.

Some, dressed in Union Jack outfits, downed champagne in the street, while others cheered as they held dolls wearing crowns.

Royal fans celebrate the news outside the Lindo Wing of St. Mary's Hospital. (Isabel Infantes/AFP/Getty Images)

“God Save the Queen!” shouted self-proclaimed town crier Tony Appleton as he rang a bell outside the hospital. Appleton, 81, is a fixture at royal events, despite having no official connection to the royal family. As well as announcing the birth of the newest royal baby, the independent town crier also took it upon himself to announce the births of both Prince George in 2013 and Princess Charlotte in 2015 — although nobody ever instructed him to.

An unsuspecting couple, who were not William and Kate, got quite the shock as they left hospital with their new baby to find the world's media waiting outside.

A couple poses with their newborn as they leave the Lindo Wing of St. Mary's Hospital, where the royal baby was born. (Kirsty Wigglesworth/AP)

Royal superfans patiently waited outside St. Mary's for a glimpse of royal baby No. 3, who is fifth in line to the throne.

Supporters of the royal family wait outside the hospital. (Henry Nicholls/Reuters)

One artist's biblical depiction of William, Kate, George and Charlotte on donkey-back caused quite a stir on social media.

Artist Kaya Mar walks past the Lindo Wing of St. Mary's Hospital with a biblical depiction of the royal couple and their children. (Frank Augstein/AP)

As with past royal baby announcements, an official notice detailing the birth was placed on an easel outside Buckingham Palace. Tourists continue to queue in the street to see the easel up close and take photographs.

A notice is placed on an easel in the forecourt of Buckingham Palace to formally announce the birth. (Stefan Rousseau/Pool via Reuters)

Much to the delight of crowds outside the hospital Prince William collected Prince George and Princess Charlotte from school and took them to meet their new baby brother. George, looking a little shy focused straight ahead as he made his way up the steps. Little sister Charlotte, however, smiled and waved at the crowds — much to their delight.

Prince William arrives at St Mary's hospital with Prince George and Princess Charlotte. (Getty Images)

“Welcome Royal baby 3" read one sign behind two supporters who sat in wait for a glimpse of the new baby. The fans also gave a nod to the coming wedding of Prince Harry and Meghan Markle with an array of royal wedding memorabilia. Harry and Meghan are set to wed May 19 in Windsor.

Supporters sit outside the Lindo Wing of St. Mary's Hospital. (Henry Nicholls/Reuters)