Prince Harry, Meghan Markle mark Prince Charles' birthday with new photo of Archie

Happy birthday, Prince Charles!

The Prince of Wales is celebrating his 71st birthday on Thursday with a flood of well-wishes from the royal family. Although the prince is spending his birthday during the two-day royal tour of India with the Duchess of Cornwall, his children took to social media to wish their father a happy birthday.

To mark the occasion, Prince Harry and Meghan Markle shared a previously unseen photo of baby Archie with the prince, which was taken during his christening back in July. Proud new dad Prince Harry is seen gazing at his newborn in his arms, while Charles looks on.

"Happy birthday to His Royal Highness The Prince of Wales - Sir, Pa, Grandpa!" the Sussexes captioned their photo. Prince William and Duchess Kate also celebrated the royal's birthday on their Instagram. The first photo, captured by photographer Chris Jackson to mark Prince Charles' milestone birthday last year, shows him playing with his grandson Prince Louis.

Another photo shared by Kensington Palace captures Prince William, Prince Harry and Prince Wales all dressed up in their traditional military gear, laughing.

Charles' younger brother the Duke of York also posted a photo of the two to Instagram to mark his big day. The black and white snapshot, which was taken in 1960, shows the Prince of Wales cradling newborn Prince Andrew in his lap.