British, Dutch and Spanish Royals gather for the Order of the Garter Service

Queen Elizabeth is seen leaving St. George's Chapel, WIndsor Castle after the Order of the Garter Service on June 17, 2019. (Photo: AP/Ben Stansall)

England's Queen Elizabeth is seen arriving at Windsor Castle for the Order of the Garter Service. (Photo: AP/Frank Augstein)

Spain's King Felipe and Queen Letizia and The Duke and Duchess of Cambridge ride to the service in a horse-drawn carriage (Photo: AP/Frank Augstein)

King Willem-Alexander and Queen Maxima of The Netherlands ride in a carriage to St. George's Chapel along with the other royals. (Photo: AP/Frank Augstein)

Household Cavalry guards march before the annual Order of the Garter Service at St George's Chapel, Windsor Castle. (Photo: AP/Peter Nicholls)

King Felipe, King Willem-Alexander, Prince Charles and Prince William, all knights of the Garter are pictured leaving the chapel. (Photo: AP/Frank Augstein)

Windsor Castle played host to the annual Order of the Garter Service. The service upholds traditions of the Most Noble Order of the Garter, the oldest surviving order of chivalry in the world. (Photo: AP/Frank Augstein)

Catherine, Duchess of Cambridge, pictured with the other royals, is seen curtsying to the Queen. (Photo: AP/Ben Stansall)

Queen Letizia of Spain and Camilla, Duchess of Cornwall chat amicably after the service. (Photo: AP/Steve Parsons)

The Duchess of Cambridge is seen sharing a light-hearted moment with Queen Maxima outside St. George's Chapel. (Photo: AP/The Times Pool/Richard Pohle)