"Happy 98th Birthday to HRH The Duke of Edinburgh. 🎉#HappyBirthdayHRH
A two-year-old Prince Charles holds The Duke’s hand after greeting his father following his return home from a trip to Malta in 1951."
"Wishing His Royal Highness The Duke of Edinburgh, Sir, Grandpa a very Happy 98th Birthday! 🎂"
Prince William and Kate Middleton took a different tack with their birthday post, sharing a series of snaps with a smiling Philip and the Queen, Philip with William and Kate, and an image of the whole family at Trooping the Colour.
Princess Eugenie's was perhaps the sweetest post of all, as she shared some seriously adorable old photos of herself and 'grandpa', alongside this touching message: "Happy Birthday to HRH The Duke of Edinburgh. I found a couple of classic photographs of Grandpa and I on Christmas Day and Trooping the Colour a few years ago now.."
While the Queen herself doesn't have an Instagram account, we're sure Her Majesty did something special for her husband's birthday!