The ever-mischievous Prince Louis is back with his cheeky antics in time for Christmas.
The youngest of Prince William and Princess Kate's children tried to blow out Princess Charlotte's candle during a special Christmas Carol service at Westminster Abbey.
Princess Charlotte, who usually keeps both brothers in line, couldn't help but laugh at Louis.
The five-year-old has entertained the nation time and time again with his funny facial expressions and tantrums.
But aside from the cheeky candle blowing, he looked well-behaved as he joined the smartly dressed Princess Charlotte, eight, and Prince George, 10, for his mother's annual Christmas concert.
Upon entering the Abbey courtyard, the royal children stopped for a moment to post Christmas cards in a special mailbox containing messages for children who may be experiencing difficulties this Christmas, something open to all young people present.
This year the service reflects the Princess's Early Years Shaping Us campaign, launched in January, which aims to highlight and promote the significance of the formative years in a child's life.
It was billed as a time to say thank you to all those who work to support babies, young children and families in communities across the UK and among the 1,500 guests were midwives and nursery teachers.
Among the highlights of the service will be composer and multi-instrumentalist Jacob Collier playing last Christmas on John Lennon's piano, which was owned by Wham! singer and solo star George Michael and loaned by his estate.
Broadcaster Roman Kemp, son of Spandau Ballet bassist Martin Kemp and former Wham! Backing vocalist Shirlie Kemp will introduce Collier and talk about the role George Michael played in her life.
Oscar-winning star Jim Broadbent will read an excerpt from Letters from Santa Claus, by Lord of the Rings author JRR Tolkien, and actor Michael Ward is expected to recount the moment an angel told the shepherds about the birth of Christ and they visited Mary and Joseph, in a reading from the Gospel of Luke.
Arriving guests were treated to carols and carols performed by the Action for Children Young Carers Aloud choir, made up of 12 young carers, including one just six years old.
Kate crouched down to talk to seven-year-old Oscar Burrow, from Lancaster, who at the age of six climbed 12 mountains raising more than £40,000 for Derian House Children's Hospice in Chorley, Lancashire.
His mother, Kimberley Burrow, said afterwards: “She said she heard about what he did and that he's doing a fantastic job, and she hopes that what he's doing inspires other kids to do amazing things.”
The service began with the popular song Once In Royal David's City, and the congregation also heard a duet from Beverley Knight and Adam Lambert who sang The Christmas Song, made famous by Nat King Cole.
William read the passage from the Gospel according to Luke that describes how Joseph and Mary traveled to Bethlehem to be registered and the birth of Jesus.
The Abbey echoed with the voices of its choir and congregation singing a selection of carols including Silent Night, Holy Night and Joy To The World, as well as Hark! The Herald Angels Sing.