Prince George birthday

The picture, taken at Kensington Palace ahead of his birthday on Saturday, captures a smiling future king.

The Duke and Duchess of Cambridge were "delighted" to share the photograph taken by royal photographer Chris Jackson, Kensington Palace said.

The prince has spent the run-up to his birthday on a tour of Poland and Germany with his parents.

Prince George Alexander Louis - known as His Royal Highness Prince George of Cambridge - was born on 22 July 2013.

On Wednesday morning, the royal guardsmen delivered an impromptu performance that would make any birthday boy happy.

"Thank you to the Grenadier Guards for playing ‘Happy Birthday' at today's Guard Change!" Kensington Palace shared on Twitter with video from the show. "#HappyBirthdayPrinceGeorge." Wonder if he was able to listen in from his play room?

Earlier this week, a palace spokesperson told E! News that "the family will be spending the day privately."