In one of the most tender royal moments in recent memory, 10-year-old Princess Charlotte stunned Buckingham with an emotional tribute to her father, King William, on his 43rd birthday. But this was no ordinary birthday toast. Stepping out under the chandeliers of the palace’s grand ballroom, wearing a floor-length sapphire gown and a delicate diamond tiara, Charlotte made her public vocal debut beside the world–renowned tenor Andrea Bocelli—leaving not a single dry eye in the room. The evening had been planned...