As she made her way up the steps, Kate turned and gave the crowd a warm wave - an iconic move perfected by her adorable three-year-old daughter.
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The only daughter of the Duchess and Prince William delighted onlookers at the christening of her baby brother Prince Louis in April 2018 by waving to crowds outside the Lindo Wing of St Mary's Hospital.
The little Princess created her trademark gesture by swiveling on the steps of the hospital and giving royal well wishers a final acknowledgment.
Charlotte rolled out her royal wave once more at uncle Prince Harry's wedding to Meghan Markle, and again at second cousin Princess Eugenie's marriage to Jack Brooksbank.
For her historic outing with Queen Elizabeth on March 20, Kate looked elegant in a grey Catherine Walker coat.
Meanwhile, Her Majesty also looked impeccable in a Stewart Parvin old rose cashmere coat with a silk dress of autumnal woodland in shades of grey, fuchsia and olive.
The monarch teamed her look with a matching Rachel Trevor-Morgan hat.