The King has sent his youngest son warm birthday greetings as Prince Harry turns 40 today.

King Charles has wished Prince Harry a happy birthday (Image: GETTY)

King Charles has offered a major olive branch to his youngest son Prince Harry as he publicly wished him a happy birthday on social media.

The Duke of Sussex celebrates his milestone birthday as he turns 40 today on Sunday, September 15.

The major birthday celebration has been marked by the reigning monarch and Queen Camilla, with a post shared on their official X account.

It reads: “Wishing The Duke of Sussex a very happy 40th birthday today!”

In the loving picture, a smiling and laughing Prince Harry is wearing a light grey suit jacket, white shirt, along with his signature bracelets – and he is caught grinning off camera. The picture is also accompanied by an emoji of a pink birthday cake.

Prince Harry was born on September, 15, 1984 (Image: Getty)

According to a well-placed source, Express.co.uk has learned the King is also set to personally reach out to his youngest son with a birthday call, potentially signalling the start of a thawing of frosty relations between the Sussexes and the Firm.

The source said that the monarch is set to call Harry via Skype on Sunday afternoon UK time so that he can catch his son as soon as he wakes up in California.

“The King will reach out to Harry on his birthday. Although the family are not as close as they once were, there is still a lot of love there.”

They added: “They tend to use Skype when they communicate because they can see each other and it’s all set up by staff so it runs smoothly.”

Meanwhile, it is thought Harry will not receive a call from his brother, Prince William. Despite their once close bond, the brothers have been in a large rift since the Duke of Sussex quit the Royal Family in 2020 and went on to make revelations about the family in tell-all interviews and his bombshell memoir Spare.

Prince Harry is thought to be celebrating on the day with his family (Image: Getty)

Royal fans have commented on the birthday picture posted by the King and Queen. X user, @kimhay1972, writes: “Happy Birthday Harry ! This is the best picture I’ve seen of him in a long time, he looks really happy & healthy.”

Another wrote: “Wishing The Duke of Sussex a joyful 40th! Here’s to another year filled with happiness and meaningful endeavors.”

A third fan said: “Happy Birthday Harry! So wonderful to see him acknowledged.”

Last year, King Charles declined to publicly celebrate Harry’s 39th birthday. The royals’ silence came after Harry released his memoir Spare, which blasted his family – including William, Kate and Camilla.

To mark his landmark birthday, rumours are swirling that Harry will be jetting off with his pals for a boys-only escapade. According to the Sun, this follows an intimate family celebration planned at his Montecito estate in California, where Meghan is expected to remain with their young ones, Prince Archie, aged five, and three-year-old Princess Lilibet.