Prince George, Princess Charlotte and Prince Louis make their first public appearance in six months

Prince George, Princess Charlotte and Prince Louis supported their mother Kate Middleton at her moving Christmas service.

On December 6, Prince William accompanied the couple’s three children to Kate’s fourth annual Christmas service at Westminster Abbey in London. The outing marks the sibling trio’s first public appearance together since “Trooping the Color” in June.

The event comes amid a challenging year for the family as Kate confronts her battle with cancer. When she announced her cancer earlier this year, Kate said she had “done everything we could to privately process and manage the illness for the benefit of our young family.” As you can imagine, this took some time.”

George, Charlotte and Louis carried notes to attach to the “Tree of Kindness” outside the venue, where guests were invited to dedicate a decoration to someone who has been a support to them in their lives.

“It’s been such a difficult year for them, it’s wonderful to see them all together,” Sophie Mirman, founder and creative director of Trotters, the brand behind Charlotte’s burgundy coat dress, tells PEOPLE.

In a candid moment at the event, Kate reflected on her challenging year, telling an artist: “I didn’t know this year was going to be the year I just had… the unplanned.”

The 42-year-old Princess of Wales chaired the first event Together at Christmas Service by the Royal Foundation in 2021 to thank those across the UK who have given back to their communities during the COVID pandemic. Since then, the concert has become an annual tradition at Westminster Abbey and a regular fixture in the royal family’s calendar.

Continuing tradition, Princess Kate was the first to arrive at Westminster Abbey, and shortly afterwards Prince William arrived with her children. Princess Kate, as hostess, is known to appear first to greet volunteers and guests before her family arrives, who usually arrive shortly before the service begins.

As last year, the Prince of Wales will give a reading at the service that includes the poignant sentence: “Those who walked in darkness have seen a great light; those who lived in a land of deep darkness – upon them is light.” shone. William’s reading of the first lesson is particularly meaningful after his wife and father, King Charles, were diagnosed with cancer in what he described as a “brutal” year.

Prince George, 11, Princess Charlotte, 9, and Prince Louis, 6, looked more grown-up than ever at the festive event, which was their second major royal appearance this year. The Welsh family coordinated in shades of red, with George and Louis wearing red ties to match Kate’s bow-tie coat by Sarah Burton for Alexander McQueen (her wedding dress designer!), while William’s tie and Charlotte’s Trotters coat (a royal repeat from…) last year) had the same burgundy tone. Ever the loving father, William placed a hand on his daughter’s back as they all walked inside.

“It’s a timeless classic, it’s very well cut and very comfortable,” Mirman von Trotters tells PEOPLE. “It is handmade in a small workshop in Portugal and literally every part of this coat is hand-sewn. It is a very extraordinary piece of work. Coats are typically mass-produced, but each coat is made by one person from start to finish. From cutting the fabric to making the buttons by hand to sewing the velvet collar.

“Charlotte looks stunning,” she adds. “It’s wonderful to see her grow up in our designs – it becomes something really special, especially on these big occasions.”

George, Charlotte and Louis were also the only children who went out with the adults. The pregnant Princess Beatrice and her husband Edoardo Mapelli Mozzi brought his son Christopher Woolf with them. Christopher Woolf is affectionately nicknamed Wolfie and, at 8 years old, is one year younger than Princess Charlotte. They walked in with Zara Tindall, who is also a mother of three with her husband Mike Tindall.

The children of the Prince and Princess of Wales last appeared together in June at Trooping the Color in the parade celebrating their grandfather, King Charles’s official birthday as ruler.

A month later, on July 14, Prince George and Princess Charlotte enjoyed special one-on-one outings with their parents – Charlotte attended Wimbledon with mother Kate, while George attended the UEFA European Championships with father William.

Last year, the Prince and Princess of Wales brought all three children to Kate Together at ChristmasPrince Louis’ First Concert was Prince Louis’ debut at the event.

Both Kate and William, 42, are committed to ensuring their children enjoy as normal a childhood as possible. A palace insider previously told PEOPLE that William “absolutely loves” the “stabilizing normalcy” that Kate brings to raising her children.

Every iteration of the Together at Christmas The Christmas service has had a unique theme so far, with Princess Kate choosing a meaningful theme after a difficult year in which she and King Charles, 77, both announced their cancer diagnoses. The royal’s treatment is ongoing, while the Princess of Wales announced in September that she had completed chemotherapy.

Kensington Palace had previously announced that the 2024 concert themes would be love and empathy, a poignant decision after a challenging period.

“This year’s service provides a moment to reflect on the importance of love and empathy and how much we need each other, especially during the most difficult times in our lives. The service will shine a light on people from across the UK who have shown love, kindness and empathy towards others in their communities,” a statement from Princess Kate’s office previously said.

The palace said 1,600 people would gather for the holiday concert at Westminster Abbey on December 6 to welcome those who have supported others in their communities through personal relationships, work or volunteering, as well as others who have experienced difficult times this year have.

The Westminster Abbey Choir Olivia Dean, Gregory Porter, Paloma Faith and JP Cooper will perform, while Prince William, Olympian Adam Peaty OBE and actors Sophie Okonedo CBE, Michelle Dockery and Richard E. Grant will give readings on the themes of love and romance will hold empathy.

Princess Kate’s holiday concert will also be celebrated with 15 community carols across the UK in December, and the Westminster Abbey pageant will be broadcast later as part of the festival Royal Carols: Together at Christmas Special broadcast on ITV1 and ITVX on Christmas Eve.

Guests at these celebrations, as well as the banner night at Westminster Abbey, received a letter from the Princess with an emotional message that love is the “greatest gift there is.”

Can’t get enough of PEOPLE’s royals coverage? Subscribe to our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

“This love is the greatest gift we can receive. Not just at Christmas, but every day of our lives. Love is the light that can shine brightly even in our darkest times. We all have something we can offer each other.” “Gentle words or a listening ear, an arm around a weary shoulder or silently at someone’s side,” the Princess of Wales said in part.

“This Christmas service is a heartfelt celebration for each of you and a reminder that we must all shine for one another at Christmas and throughout the year,” she later wrote in the letter. “For in times of joy and sorrow, we are each other’s light.”

Dive into royal holiday traditions with the special edition of PEOPLE: Christmas at the Palace: A Royal Family Album.