Prince Andrew, Duke of York, hosted an entrepreneurial presentation at St. James's Palace on Monday, but he surprised the audience when he decided to sing "Happy Birthday" to his daughter Princess Eugenie via a video call. Holding an iPad, he told the crowd of 400 that they would do some "audience participation." His daughters, Princesses Eugenie and Beatrice, then appeared on the screen along with his ex-wife, Sarah Ferguson. As a guardsman played the trumpet, Prince Andrew and the audience belted out the sweet song to the princess, who sported festive sunglasses for her 25th birthday. Watch the cute moment above, and then see the best pictures of Princess Eugenie through the years [1], plus 49 facts every die-hard fan of the British royals should know [2].