An official picture has been released to mark the fourth birthday of Prince George – and the future king looks a happy little boy.

George beams out of the portrait taken at Kensington Palace ahead of his birthday, which the youngster will celebrate on Saturday.

The prince spent the run-up to his big day on an official tour of Poland and Germany with his parents, the Duke and Duchess of Cambridge.

Kensington Palace said in a statement: “The Duke and Duchess of Cambridge are delighted to share a new official portrait of Prince George to mark His Royal Highness’s fourth birthday tomorrow.

“The photograph was taken at Kensington Palace at the end of June by Chris Jackson, Getty Images Royal Photographer.

“The Duke and Duchess are very pleased to share this lovely picture as they celebrate Prince George’s fourth birthday, and would like to thank everyone for all of the kind messages they have received.”

Photographer Chris Jackson said Prince George Photographer Chris Jackson said Prince George “certainly injects some fun into a photoshoot” (Chris Jackson/PA)

Mr Jackson said: “I’m thrilled and honoured that the Duke and Duchess of Cambridge have chosen to release this portrait to celebrate Prince George’s fourth birthday.

“He is such a happy little boy and certainly injects some fun into a photoshoot!”

William and Kate’s eldest child has a busy year ahead of him as he starts school in September.

The Duchess has already said she is not sure George, who will be young for his year, “has any idea what’s going to hit him” as he begins full-time education.

George is joining private day school Thomas’s Battersea in September, where fees cost £17,604 a year.

(Jonathan Brady/PA)George is to attend Thomas’s Battersea from the autumn (Jonathan Brady/PA)

The selective establishment states that its most important rule is to “be kind”. Its 540 pupils are aged from four to 13, with around 20 in a class.

Art, ballet, drama, ICT, French, music and physical education are all taught by specialist teachers from a child’s first day in school.

The Cambridge family will be based at Kensington Palace in London, rather than at their Norfolk mansion Anmer Hall, with William leaving his air ambulance helicopter pilot job this summer to become a full-time royal.

George showed himself to be something of a shy royal diplomat when he arrived in Warsaw, needing encouragement from William to exit the plane, and fidgeting on the red carpet.

According to Kate, the prince is a “noisy” youngster and a “really lovely little boy” whom she hopes will keep “feisty” younger sister Princess Charlotte in check.