Prince William and Catherine's youngest son, Prince Louis, turned 5 last month — and he was spotted yawning during the coronation of his grandfather, King Charles, before making a preplanned departure.

Louis and his older sister, Princess Charlotte, smiled and waved at the crowds. According to the Daily Telegraph, it appeared that Louis said "I'm waving" as he arrived in the state car.

Louis then took his seat between his mother and his sister. According to ITV, he was expected to "retire" given that the service was two hours long. He was absent briefly before being spotted again as King Charles and Queen Camilla were walking out of the ceremony.

After the coronation, Louis rode in a coach with his family from Westminster Abbey to Buckingham Palace.

His grandfather, King Charles, was 4 years old during his mother's coronation and only attended part of it due to his young age — even though he was next in line for the throne at the time. In photos from the balcony, he could be seen looking bored. Charles' sister, Princess Anne, who was 2 at the time, did not attend. 

Louis, who is currently fourth in line for the throne, has stolen the show before at royal ceremonies. During Queen Elizabeth's Platinum Jubilee last year, he was spotted dancing and waving, and memorably covering his ears during the flyover from the balcony. William and Catherine cheekily tweeted after the ceremony "we all had an incredible time … even Louis."  

Where were William and Kate's other children for the ceremony?

William and Catherine's oldest child, 9-year-old Prince George, served as Page of Honor during the ceremony and was not seated with his family. Princess Charlotte, who turned 8 this week, walked in with Louis and sat with her parents during the ceremony. 

Where were Charles' other grandchildren? 

Charles' other grandchildren, Prince Harry's children, Prince Archie and Princess Lilibet, who are 4 and 1, are not attending the ceremony. Neither is their mother, Meghan, Duchess of Sussex. 

Who were the other children at the coronation? 

Camilla's grandsons, Gus Lopes, Louis Lopes and Freddy Parker Bowles, who are all 13, served as Pages of Honor for Camilla. Her great-nephew, Arthur Eliot, also served as Page of Honor. 

In:
• King Charles III
• William Prince of Wales
• Queen Camilla
• Coronation
• Catherine Princess of Wales