Prince William, Kate Middleton, Prince Harry, and the Duchess of Sussex helped celebrate the 100th anniversary of the Royal Air Force.
The Duchess of Cambridge, 36, catches the prince giggling, and she too attempts to contain her laughter.
A day crowded with royal ceremony began with a special service in Westminster Abbey, followed by a parade in The Mall, the traditional roaring fly past over the palace, plus receptions later.
They include Meghan's hairdresser George Northwood, who did her relaxed updo at the couple's evening wedding reception.
The Duchess then arrived in Dublin with her husband, Prince Harry, for their first official overseas trip wearing an emerald green Givenchy skirt and top paired with tan heels and a Strathberry bag.
A trio of F-35B Lightning II aircraft of 617 Squadron taking part in the RAF100 flypast over London to mark the centenary of the RAF.
The Royals arrive at Westminster Abbey to mark 100 years of the RAF, ahead of the flypast. Queen Elizabeth II and Prince Philip were notably absent from the prince's christening at St. James's Palace on Monday.
They will meet Irish President Michael D. Higgins before visiting an Irish emigration museum, a technology startup hub and Trinity College, Ireland's oldest university.
Later today, Meghan and Harry will fly to Dublin where they'll spend the next two days.
The Royals watched as Typhoons formed the shape of the number 100 in the sky, before the Red Arrows - the RAF's aerobatic team - concluded the show, vapour-trailing the red, white and blue of the Union Jack flag.
The RAF, which is the first-ever independent air force, split from the British Army and Royal Navy in April 1918.