It was a moment that "blink and you might miss it," but nonetheless a sign of great respect.

Last Tuesday, as Her Majesty turned to take her seat at Westminster Abbey to attend a service of thanksgiving for her late husband Prince Philip, viewers with a keen eye on the memorial caught the Duchess of Cambridge bowing low to the Queen as the monarch passed to Kate's left.

Kate, seated with her husband Prince William and three of their children, Prince George and Princess Charlotte, drew attention as she entered the abbey in a polka-dot Alessandra Ricci dress (the second time she has worn this designer in as many days). Many, however, missed Kate's gesture. The gesture was a natural manner for a royal lady who was meeting Her Majesty in public for the first time that day. (On the other side of the aisle, Sophie, Countess of Wessex, the Queen's daughter-in-law, and Lady Louise, daughter of Prince Edward and Sophie, also bowed. (If you are wondering why the other royal ladies did not bow as Her Majesty the Queen passed by, it is probably because they had already seen her earlier in the day.)

In addition to the Cambridges and the Wessexes, Prince Charles and his wife Camilla, Princesses Anne, Beatrice, and Eugenie, and, perhaps infamously, Prince Andreu, who escorted his mother to her seat at the abbey, were also present.