At one point in the waiting period, Charlotte, 7, appeared to remind her 9-year-old brother what to do when the coffin passed by.
In a short video, Charlotte told her older brother, "You need to bow." As she delivered the friendly reminder, the second in line for the throne listened intently.
When the Queen's coffin passed by the royal family, George followed royal protocol—and his sister's advice—by bowing right on time.
During the Queen's state funeral at Westminster Abbey, William and Kate's youngest child, Prince Louis, 4, remained at home. In addition to Louis likely not attending because of his young age, Kate revealed just a few days before the service that Louis had trouble understanding the significance of his great-grandmother's death.
In particular, the Princess of Wales revealed that Louis was curious about how the Queen's death would affect their annual family trips to Balmoral Castle in Scotland.
In the wake of the monarch's death, William and Kate have been open about how their children are grieving the Queen's death. Last week, the couple spoke to members of the public who were paying their respects to the late monarch at Sandringham Estate.
In one Twitter video, the Princess of Wales said her three children are "being well looked after" before adding, "They're in a routine and they're happy. They're with new friends."
William echoed his wife's sentiments, stating in another video that, "We're trying to keep everything constant and settled for them."