So handsome! Prince George flashes toothy grin in new photos marking his sixth birthday

Prince George of Cambridge, future king, cute as a button, turns 6 on Monday, giving millions of Brits and American fans a chance to coo over the latest birthday pictures released by his parents.

Prince William and Duchess Kate of Cambridge released three new photos late Sunday, following a custom they started for George's first birthday and have followed for their two younger children, Princess Charlotte, 4, and Prince Louis, 1, on their birthdays.

The recent pictures, which were shot in the garden of the family's home at Kensington Palace and while they were on holiday, were taken by his mother. Kate, a keen amateur photographer, often takes the pictures of her children released to the public.

"The Duke and Duchess of Cambridge are very pleased to share new photographs of Prince George to mark His Royal Highness's sixth birthday," the palace tweeted. "Thank you everyone for your lovely messages on Prince George’s Birthday!"

Prince George looks so grown in this new birthday shot taken by Duchess Kate.
Prince George looks so grown in this new birthday shot taken by Duchess Kate.

In the family vacation photo, George wears a dark green polo shirt with blue-and-white striped shorts and looks more like his dad, as his hair lightens.

The other two shots are the playful George, romping in the grass in a Nike soccer jersey, that royals fans have come to love.

George is a student at Thomas's Battersea school across the Thames from Kensington Palace. His sister Charlotte is set to join him there in the fall.

Prince George Alexander Louis is third in line to the throne, after his father Prince William, 37, and grandfather Prince Charles the Prince of Wales, 70. He isn't the oldest great-grandchild of Queen Elizabeth II, 93, but he is the one most likely to be a king, some day in the far future.

Fans got their first glimpse of the little prince back in 2013, when he was introduced to the world on the steps outside St. Mary's Hospital in London, the evening after his birth.

He was last seen in public with his mother and siblings, and with his aunt, Duchess Meghan of Sussex, and his newest baby cousin, Archie Harrison Mountbatten-Windsor, earlier this month at a charity polo match in which Prince William and Prince Harry were competing.

Over the years, these charity polo matches have been reliable opportunities to catch the Cambridges together at play and relaxing in "private" moments that are nonetheless in the open and thus accessible to media photographers and paparazzi.

Contributing: Kim Willis

This article originally appeared on USA TODAY: Prince George turns 6: See cute new birthday photos of the future king