- Prince Louis attended Trooping the Colour alongside Kate Middleton, Prince William, and his siblings.
- The 4-year-old wore a white and blue sailor outfit to mark the Queen's official birthday.
- His father, Prince William, wore an identical outfit to Trooping the Colour in 1985.
Prince Louis re-created one of Prince William's earliest looks at the 2022 Trooping the Colour.
The royal family is celebrating Queen Elizabeth's Platinum Jubilee this week, and the festivities for her unprecedented 70 years on the throne kicked off on Thursday with Trooping the Colour, the monarch's annual birthday parade, in London.
Every senior member of the royal family attended the parade, including Prince William and Kate Middleton as well as Prince Harry and Meghan Markle, though the latter pair did not join the rest of the family on the Buckingham Palace balcony.
Prince George, Prince Charlotte, and Prince Louis also attended their great-grandmother's parade, arriving in a carriage with their mother and the Duchess of Cornwall.
All three children wore shades of blue in the rare public appearance.
Louis, 4, arrived in a blue and white sailor's outfit complete with a tie.
Louis' look might be familiar to eagle-eyed royals fans, as the ensemble is almost identical to the outfit Prince William wore to Trooping the Colour in 1985.
The mini sailor outfit isn't the first time one of William's children has matched one of his looks.
For his brother Louis's christening in 2018, George wore a button-down shirt and shorts that mimicked William's outfit for Prince Harry's christening in 1984. And at a 2021 soccer game, William and George wore matching suits.
The four-day Platinum Jubilee celebrations will continue throughout the weekend, and it seems the celebrations will reach their peak at the "Platinum Party" on Saturday, where some of the "world's biggest entertainers" will perform, according to the BBC.
Kensington Palace did not immediately respond to Insider's request for comment.