The queen appeared in a sketch before the festivities got underway.
Lilibet turned 1 on Saturday but the Duke and Duchess of Cambridge were in Wales for other engagements.
Queen Elizabeth and Kate Middleton shared messages on social media.
Meghan Markle and Prince Harry were seen seated far away from Kate Middleton and Prince William at the latest Platinum Jubilee event.
A source confirms to ET that Queen Elizabeth II finally met Prince Harry’s little girl, Lilibet, at Trooping the Colour on Thursday.
The couples did not sit side-by-side at the Platinum Jubilee Service of Thanksgiving.
The monarch met Prince Harry and Meghan Markle's daughter in person ahead of her first birthday.
Meghan Markle and Prince Harry stepped out for the kickoff of Queen Elizabeth's Platinum Jubilee celebration.
The visit marks their first trip back to England as a family since making their royal exit in January 2020.
The siblings were accompanied by their mom, Kate Middleton, and Camilla, Duchess of Cornwall.
After a year of celebrations held across the Commonwealth, the UK will enjoy a four-day bank holiday from June 2-5.
The Duke and Duchess of Sussex won't join Queen Elizabeth on the balcony of Buckingham Palace.
While Queen Elizabeth is set to meet Harry and Meghan's daughter, Prince William and Kate Middleton will be away on an engagement.
The Duke and Duchess of Sussex are expected to stay at their former residence while in the UK for the Queen's grand celebration.
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