Princess Elizabeth with her husband Prince Philip Duke of Edinburgh and their children Prince Charles and Princess Anne. (Photo by Keystone/Getty Images). August 1951

Prince Philippe and Princess Letizia of Spain meet with Israeli president Shimon Peres at the presidential residence on April 11, 2011 in Jerusalem, Israel. The Spanish Royal couple is on their first official visit to Israel together. The Prince's parents, the King and Queen of Spain last visited in 1993.

Prince Harry and Pippa Middleton look-a-likes stage a walkabout In Soho to launch Alison Jackson's new book 'EXPOSED' on December 7, 2011 in London, England. (Photo by Ben Pruchnie/Getty Images)

A Rolls-Royce state car at the Royal Mews on March 21, 2011 in London, England. The car will transport Prince Charles, Prince of Wales and Camilla, Duchess of Cornwall on the day of the wedding of Prince William and Kate Middleton. (Photo by Dominic Lipinski - WPA Pool/Getty Images)

A horse named Quinn, with a skeleton painted on it to help educate officers, is pictured during a visit by Britain's Queen Elizabeth II (unseen) and Britain's Prince Charles, Prince of Wales (unseen) to the Household Cavalry Mounted Regiment at the Hyde Park Barracks in west London on October 24, 2017. (Photo by Chris Jackson/AFP Photo)

Boys in ceremonial uniform at the civil wedding ceremony of American actress Grace Kelly and Rainier III, Prince of Monaco at the Prince's Palace of Monaco, 18th April 1956. Original publication: Picture Post - 8336 - The Hour Of Marriage - pub. 28th April 1956.

Britain's Prince Harry meets Chewbacca during a visit to the Star Wars film set at Pinewood Studios near Iver Heath, west of London, Britain, April 19, 2016. Prince William and Prince Harry are touring Pinewood to visit the production workshops and meet the creative teams working behind the scenes on the Star Wars films. (Photo by Adrian Dennis/Reuters)

Revellers take a break during the Carnival 2016 parade in Port-au-Prince, Haiti, February 8, 2016. (Photo by Andres Martinez Casares/Reuters)