Adorable Prince Louis' eyes light up at mention of Santa as he sings carols at mum Kate's Together at Christmas service

THIS is the adorable moment Prince Louis’ eyes lit up at the mention of Santa after he joined his mum Kate for the royal celebration.

Playful Louis was on his best behavior for the service, which aired last night.

Prince Louis’s eyes lit up at the mention of Santa Claus

Prince Louis sang Joy to the World with his siblings Credit: itv

The Prince was on his best behavior on Sunday Credit: Rex

Louis, Charlotte and George sent letters to Santa Claus

Kate hosted the service at Westminster AbbeyCredit: Rex

Fans of The Firm couldn’t help but notice how his eyes lit up when actor Jim Broadbent read JRR Tolkien’s The Father Christmas Letters.

Louis was said to have “Christmas magic in his eyes” as he nudged Kate and whispered “mummy” as the message was read out.

He was caught sensibly holding a candle during the service, including 1,500 people.

The Princess of Wales hosted her Christmas Eve bash at Westminster Abbey – attending alongside her family and music celebrities.

The gala included performances by stars such as Beverley Knight, Freya Ridings and James Bay.

This year the service focused on the vital importance of early childhood.

It was also a moment to thank those who supported the youngest members of our society during those crucial early years, as part of the Shaping Us campaign.

Kate was accompanied by Prince William, who was reading the Bible, and their three children, ten-year-old George, eight-year-old Charlotte, and five-year-old Louis.

Winning the hearts of the nation as always, the cute young royals sang Joy to the World with their siblings.

The theme of Kate’s annual television spectacle was ‘children and families’ after the princess launched her Shaping Us project this year to help under-5s.

And in a touching behind-the-scenes video shown on ITV, Kate dressed in a festive red and white jumper to meet 13-year-old Ric and Russell Gray, his coach, in Manchester.

Sources say the friendship helped Rico by building his confidence and allowing him to pursue his passion for football.

A smiling Kate, 41, appeared on screen at the tea party shaking the young man’s hand and saying: “Hi Rico, nice to meet you.

She asked, “Seeing and building this relationship with Mr. Gray, has that helped you in your relationship with your friends?”

Rico, wearing a green sweater emblazoned with a football and a Santa hat, replied, “It brings trust because if you can trust one person then you can trust more people.”

Russell Gray told Kate: “If you can give them confidence, responsibility, increase their self-esteem, which football and teamwork do, then you’ve done a good job.

“You should try to give something back, especially to the children, because that’s where everything starts.”

The Together at Christmas service is supported by the Royal Foundation.