The queen's gesture is remarkable for a couple of reasons; first, while it is customary for others to bow (or curtsy) to her majesty, she is not technically required to bow or curtsy to others. She made a solemn, unexpected acknowledgment to her former daughter-in-law's casket that she rarely does for anyone else.
Second, there was a huge amount of drama within the royal family after Diana's death, including the fact that Queen Elizabeth II had insisted that Diana's ceremony be private — she faced "fierce resistance" from Prince Charles, and then-British Prime Minister Tony Blair also agreed that Diana should be laid out at St. James's Palace with a public funeral held at Westminster Abbey. Because the queen was so highly criticized for her silence and "business-as-usual" behavior in the wake of Diana's death, her bowing at the coffin attempted to send a message of compassion, honor, and genuine grief.
