Prince Louis looked uncharacteristically shy when he joined his older siblings and the rest of the royal family at their annual Christmas Day church service. Making his festive debut, little Louis walked into St Mary Magdalene Church in Sandringham hand-in-hand with his proud parents, the Prince and Princess of Wales.
But some fans were left puzzled as to why the four-year-old was wearing shorts in the chilly December temperatures, especially as his big brother George was wearing trousers.
It turns out William and Kate's outfit choice was down to a very upper class tradition which dates back centuries.
Etiquette expert William Hanson has previously told Harper's Bazaar that royal boys are normally dressed in shorts for formal occasions until their eighth birthday. He explains: "Trousers are for older boys and men, whereas shorts on young boys is one of those silent class markers that we have in England.
"Although times are (slowly) changing, a pair of trousers on a young boy is considered quite middle class – quite suburban.
"And no self-respecting aristo or royal would want to be considered suburban."
Louis isn't the only one and most royal men donned shorts when they were younger. George wore them to pretty much every royal engagement for the first years of his life, but he's now nine which means he's been upgraded to trousers.
Princes William and Harry also wore them when they were boys, and old photos show the late Queen dressed her children - including King Charles - in the same style.
King Charles led his family into the church as they navigated their first festive season without the late Queen.
As well as the Wales family, he was joined by Queen Camilla, Zara and Mike Tindall, Edward and Sophie Wessex with Lady Louise Windsor and James, Viscount Severn as well as Princess Beatrice, her husband Edoardo Mapelli Mozzi and his son Wolfie.
Disgraced Prince Andrew also made an unexpected appearance at the religious event, seen alongside his youngest daughter Princess Eugenie and her husband Jack Brooksbank.
Prince Louis stole the show at the Platinum Jubilee celebrations in June, however he was more reserved at last week's festive event. At one point, he was seen tugging his mum Kate's hand as she chatted to well-wishers, seemingly keen to get back to their Sandringham estate for more Christmas excitement.
But body language expert Judi James claims she spotted a very sweet moment when the youngest appeared to comfort his grandmother, Camilla.
Speaking to The Mirror, Judi told how Camilla's body language often seems quite 'tense' and 'nervous' when she is in public and December 25 was no exception to this.
"Camilla's body language signals suggest she is often in a state of tension or nervousness in public," she explained.
"When the royals emerged from the church Charles appeared to be in high spirits, pointing to and laughing with the clergy but leaving Camilla trailing in his wake.
"Her repeated eye-dart rituals as she tried to position herself alongside her husband reflected inner tension or awkwardness and the way Louis stepped away from his parents to join her and chat to her suggested he was keen to cheer her up with some company and help her relax."
Judi added: "Louis' body language is still very spontaneous and small children can often feel or sense when someone needs company.
"He was also busy later showing this side of his personality as he called for his picture of Paddington to be shown to a small girl and rushed up to Charlotte with a small bouquet of flowers."
