The royal family has celebrated King Charles ' 77th birthday by releasing a photo of the monarch relaxing at his Sandringham estate .

The image and accompanying post was released overnight via The Royal Family' s official Instagram page.

"77 today!" the post read. "Thank you for the kind words and well wishes on His Majesty's Birthday."

Watch the video above.

But while the King was seen relaxing in the picture, there was no time for him to put his feet up on the day, with Charles undertaking a number of official engagements in Wales.

First on the agenda was a visit to Taff's Well Transport Depot, where the King took the controls of a tram-train within the depot.

He also unveiled a plaque to officially open the South Wales Metro Depot and spoke to waiting school c

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