Traditional gun salutes marked the arrival of a new prince as the Duke and Duchess of Cambridge settled into life as a family of five after welcoming their third son into the world.

Eastern Daily Press: The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: Dominic Lipinski/PA WireThe Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: Dominic Lipinski/PA Wire

After proudly showing off their newborn baby to crowds gathered outside St Mary's Hospital, Paddington and the world's media, the couple retreated to the sanctuary of Kensington Palace to adjust to a new life.

The couple were expected to welcome friends and visitors to meet their latest child, while celebrtities such as Holly Willoughby, Liam Payne and Ellen DeGeneres sent their congratulations.

Traditional gun salutes from the Tower of London and Hyde Park commemorated the birth, along with bell ringing at Westminster Abbey.

It was not known when the prince will meet his great-grandmother the Queen, 92, who is still at Windsor Castle for Easter Court, while the Duke of Edinburgh is recuperating following a hip operation.

Eastern Daily Press: The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: Aaron Chown/PA WireThe Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: Aaron Chown/PA Wire

However Kate's sister Pippa was photographed driving to Kensington Palace, presumably to meet the little one for the first time.

Prince George and Princess Charlotte visited their new sibling at the hospital in London shortly after the birth on Monday afternoon.

A confident and excited Charlotte, who turns three on May 2, turned to wave at the photographers outside the hospital as she led the way up the steps holding William's hand.

Four-year-old George, in his school uniform, appeared more wary of the huge crowds of media.

Eastern Daily Press: The Duchess of Cambridge with her newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: John Stillwell/PA WireThe Duchess of Cambridge with her newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: John Stillwell/PA Wire

During his first photocall, the baby - who was wrapped in a white lace shawl with a matching bonnet - could be seen moving his fingers as he was cradled by Kate.

Smiling broadly, the duchess was dressed in a vibrant red Jenny Packham dress with a white lace collar, reminiscent of William's late mother Diana, Princess of Wales - who wore red and white outside the Lindo Wing after Prince Harry was born in 1984.

As William and Kate headed home after appearing in front of the banks of cameras with their seven-hour-old son, the Duke said they were 'very happy' and 'very delighted'.

He joked, holding up three fingers, that he had 'thrice the worry now', adding: 'We didn't keep you waiting too long this time.'

Eastern Daily Press: The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: David Mirzoeff/PA WireThe Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: David Mirzoeff/PA Wire

The Duke and Duchess thanked the hospital for their care and the public for their wishes.

Eastern Daily Press: The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: David Mirzoeff/PA WireThe Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: David Mirzoeff/PA Wire

Eastern Daily Press: The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: John Stillwell/PA WireThe Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing at St Mary's Hospital in Paddington, London. Picture: John Stillwell/PA Wire