Sarah shared a picture of the royal on her Instagram account with the accompanying caption: "So proud of the new Colonel of The Grenadier Guards @hrhthedukeofyork".
Prince Harry is relegated to a spot in a carriage because he is not a royal colonel.
Meghan's dress was a gorgeous, custom-made pale pink Carolina Herrera dress and her Philip Treacy hat was matching.
He is now recovering from a hip replacement, but was well enough to be able to his attend the wedding of Prince Harry and Meghan Markle three weeks ago.
It's official - Meghan Markle is part of the British Royal Family.
Trooping the Colour, staged every June by London's Horse Guards Parade, has commemorated the birthday of the sovereign for more than 250 years. Over 1400 soldiers were in the ceremony, a tradition originating from the preparations for battle where the Regimental Colour or flag is "trooped" down the ranks of the soldiers so they can see them.More news: North Korea-US summit scheduled for morning of June 12: White House
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QE2 and her crew busted out their best royal waves for the festivities, which included a Royal Air Force flyover, and a carriage parade of the whole family.
The members of the royal family - yes, including now Meghan Markle, the Duchess of Sussex - stepped out on Saturday in London for the annual Trooping the Colour parade, the official celebration of Queen Elizabeth II's birthday. As well, if the Queen can't guide her, then expect to see the guiding hand of a lady-in-waiting who acts as a female regal aide on such duties.
Kate, taking a break from her maternity leave with Prince Louis after his April 23 birth, wore an Alexander McQueen dress with Juliette Botterill fascinator. In January, the new royal wore a plaid Theory blazer that offered a hint of collarbone, and at her wedding to Prince Harry last month, her custom Givenchy gown mimicked a similar neckline.