Although Kate, 36, isn't due to return to work until September, she chose to make an appearance at the event after RAF made her an Honorary Air Commandant in 2015, passing the role from Prince Phillip to her, according to the Mirror.
Queen Elizabeth II kicked off a day of engagements in a pair of patent leather heels, but switched into her comfortable favourites later on in the day.
Keep scrolling for some of the best pics of the day! The two attended Eton together, and he was an usher at William and Kate's 2011 wedding.
Meghan was christened and confirmed in the oak-panelled Chapel Royal by the archbishop, who also married her and Harry in May.
"Emerging reports suggest that the departing aides left due to their roles being merged into one - but speculation has been fuelled just one week after the government performed a dress rehearsal for the Queen's death under its code name, London Bridge", reports Heart.
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Better with Moment cases: The only app specifically created to work with the Moment Battery Photo Case and Original Photo Case. To commemorate the event, Apple not only released the stunning iPhone X , but a major redesign to the App Store as well.
"It was made from scratch, from sketching it out, to embroidering the lace on a special silk-based tulle", aide Angela Kelly told PEOPLE.
A video clip doing the rounds on social media is a bit hazy, as Charlotte passes behind a pillar and is momentarily obscured from view, but it's been claimed Charlotte looked at one of the photographers directly and said: "He's not coming!"
Catherine, Duchess of Cambridge and Princess Charlotte of Cambridge arrive at the Church of St Mary Magdalene on the Sandringham Estate for the Christening of Princess Charlotte on July 5, 2015.
Kate has been on maternity leave since the birth of Prince Louis, who was born on April 22, 2018.
What did Prince George wear?
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