Sarah, Duchess of York and Princess Eugenie have posted their birthday wishes to the Duke of York.
Andrew, who is the Queen and the Duke of Edinburgh’s second son and third child, is celebrating turning 59.
The duchess tweeted a photo of the duke, wearing a shirt, tie and a woolly cardigan, and smiling as he peered over the top of his round tortoiseshell glasses.
Writing “Happy Birthday Andrew” followed by a partying face emoji, Sarah also included a picture of the duke in military uniform inspecting guards.
The duke and duchess divorced in 1996, but remained best friends as they brought up Eugenie and her older sister Princess Beatrice, prompting speculation they might one day remarry.
Eugenie, whose royal wedding last year to drinks executive Jack Brooksbank prompted much celebration for the Yorks, paid tribute to her father.
Alongside a black and white photo of Andrew as a toddler being carried by the Queen, she wrote: “Happy Birthday to you Papa … we are so proud of you in everything you have achieved in your 59 years!!”
The Royal Family’s Twitter account also wished the duke a happy birthday, with a picture of him in top hat and tails, riding in the royal carriage procession with the Queen at Ascot.
Prince Andrew Albert Christian Edward was born at Buckingham Palace on February 19 1960.
He arrived after a gap of almost 10 years between him and Princess Anne, and became the first child to be born to a reigning monarch for more than 100 years since Queen Victoria’s last, Princess Beatrice, in 1857.
When the Duke and Duchess of Sussex’s baby arrives in late spring, the duke – once the spare to the heir – will drop down from seventh to eighth in line to the throne.