The past 12 months have been an exciting period for George, from completing his first school year to once again joining his great grandmother the Queen on Buckingham Palace's balcony to mark her official birthday.

The future king is likely to spend the weekend celebrating his big day, which falls on Sunday, with his parents the Duke and Duchess of Cambridge.

But according to reports, the party may be in the Caribbean as William and Kate are rumoured to have taken their children on a summer break to the exclusive island of Mustique.

Prince George Alexander Louis of Cambridge was born at the private maternity wing of St Mary's Hospital, Paddington, the Lindo Wing, at 4.24pm on July 22, 2013, weighing 8lbs 6oz.

He made his public debut in front of the world's media on the hospital steps one day later, wrapped in a white merino wool shawl, cradled in his proud parents' arms.

A few months after his last birthday George started his first day at school with dad William, but was without mum Kate. She was experiencing severe morning sickness as she was pregnant with Prince Louis.

George was last seen at the christening of his baby brother Louis at the Chapel Royal at St James's Palace on July 9, and in official photos marking the royal baptism.

His birthday photo was taken on that day.

He will be the 43rd monarch since William the Conqueror obtained the crown of England if, as expected, he follows the reigns of the Prince of Wales, then William.

Australian Associated Press