The Princess of Wales enlisted the help of recently widowed Lady Gabriella Windsor to plan her Westminster Abbey carol service this year.
Lady Gabriella, whose husband Thomas Kingston took his own life in February, helped choose which musical performances would be featured at the annual Christmas event.
The BBC understands that King Charles’ second cousin enjoyed her role in the service and was excited to take part after a difficult year.
On December 6 this year, Catherine made her biggest return to royal duties after completing chemotherapy. The event was dedicated to individuals who have shown love, kindness and compassion to their communities.
The Princess of Wales asked Lady Gabriella to join Catherine over the summer, who is understood to be incredibly grateful for her support.
Lady Gabriella is the daughter of Prince and Princess Michael of Kent – with Prince Michael, 81, the grandson of King George V and first cousin of the late Queen Elizabeth II.
Lady Gabriella’s husband, Financier Thomas Kingston, died of head injuries. At his parents’ house in the Cotswolds. In October, a coroner concluded that he took his own life at the age of 45.
In a tribute at his death, Lady Gabriella and his family described Mr Kingston as “an extraordinary man who brightened the lives of all who knew him”.
The Christmas message at this year’s service was about promoting “love, not fear.”
“Love is the light that can shine even in our darkest times,” the princess wrote in a letter to guests.
It marked the end of a difficult year for her and her family, with both Catherine and King Charles undergoing cancer treatment.
The Prince and Princess of Wales. They were joined by their children. Prince George, Princess Charlotte and Prince Louis at the service.
The 1,600-strong congregation held candles during the service, which will be broadcast by ITV on Christmas Eve.
The world-renowned Abbey Choir performed a number of carols and the program featured performances by Paloma Faith, Gregory Porter, Olivia Dean, and singer-songwriter JP Morgan who performed with the Soul Century Choir.
Readings were given by actor Richard E. Grant, Olympic swimming gold medalist Adam Petty and Downton Abbey star Michelle Dockery.
It will feature three films about people and organizations that have inspired and comforted others in times of need.
In a pre-recorded opening address, Catherine will read excerpts from a letter she wrote about love and compassion that was included in the ceremony’s setting service.
She will say: “The Christmas story encourages us to consider the experiences and feelings of others.
“It also reflects our own weaknesses and reminds us of the importance of giving and receiving compassion, as well as how much we need each other despite our differences.
“Above all, it encourages us to turn to love rather than fear. The love we show ourselves and the love we show others. The love that listens with compassion, the love that is kind and understanding, the love that forgives, and the love that brings joy and hope.”