Prince Louis made his debut at Princess Kate’s new holiday tradition — and had a funny moment with one of his siblings

Another Prince Louis outing, another adorable moment!

Kate Middleton and Prince William’s youngest child joined his family at the third annual Christmas carol concert at Westminster Abbey on Friday evening, marking his debut at the holiday event.

Just like older siblings Prince George and Princess Charlotte, 5-year-old Louis joined the congregation in holding lit candles for the end of the service — and was caught blowing out his sister’s flame as they exited!

In a photo of the moment, Prince Louis leans over with puffed cheeks to blow out Princess Charlotte’s candle — and behind them, Princess Kate appears to catch his cheeky move.

In a video shared by Prince William and Princess Kate’s team on social media of the Christmas concert, Kate leans down to light her youngest child’s candle with the one she was holding.

While most members of the congregation held both a candle and a program, Prince Louis focused solely on his candle!

Thank you to everyone who has been a part of our special carol service, Together at Christmas.

From the performers whose voices filled Westminster Abbey, to the early years workforce of carers, midwives, nurses and so many more who are not only making a difference to children… pic.twitter.com/JxTFfabG0x

— The Prince and Princess of Wales (@KensingtonRoyal) December 8, 2023

This isn’t the first time Prince Louis has stolen the spotlight at a royal event. In May 2023, the little prince went viral for a photo that captured him yawning during his grandfather King Charles’ coronation.

Previously in June 2022, during Queen Elizabeth’s Platinum Jubilee, a photo circulated of the prince covering his ears and yelling as the Royal Air Force planes noisily passed overhead while he joined the royals on the Buckingham Palace balcony.

The same weekend, Prince Louis’ antics during the Platinum Jubilee Pageant went viral — prompting acknowledgment from his parents. Kate and William ended the of celebrations for Queen Elizabeth’s 70 years on the throne by sharing a social media post that said, “We all had an incredible time, especially Louis…”

Louis is “a cheeky monkey — a typical third child,” someone who knows the family previously told PEOPLE. “It’s nice that the world got to see him enjoying himself.”

Prince Louis’ outing at the Christmas carol concert was likely especially meaningful for Princess Kate, as her whole family was there to support her in hosting the holiday event during its third year. After kicking off the new tradition in 2021, the Princess of Wales was joined by Prince George and Princess Charlotte last year.

Before heading into Westminster Abbey for the holiday event, George, Charlotte and Louis had an important task: mailing special letters. Children were encouraged to send Christmas cards and best wishes to other children who might be struggling this year. The trio headed over to a red mailbox outside the venue and dropped their letters inside before joining their parents for their entrance. According to royal reporter Rebecca English, George, Charlotte and Louis all wrote their own cards.

While Prince George, 10, and Princess Charlotte, 8, have accompanied their parents at royal events for several years, Prince Louis is only recently old enough for such outings. In 2019, George and Charlotte made their Christmas Day debut alongside the royal family for their annual walk to church services — and last year, Prince Louis joined for the first time!

This year’s Christmas concert — featuring performances by Westminster Abbey’s choir, Adam Lambert, Beverley Knight and more as well as a reading given by Prince William — is linked to Princess Kate’s Shaping Us campaign, which focuses on her mission to support children during the early years of their lives. The palace said the event was organized to “thank all those who work to support babies, young children and families in our communities across the U.K. and a celebration of the golden opportunity that the birth of a new baby brings.”

The event will be broadcast as part of Royal Carols: Together at Christmas, airing on ITV1 and ITV X on Christmas Eve.