by 
AARON CHOWN/POOL/AFP via Getty Prince William and Prince Harry
Prince William and Prince Harry joined in a message to a special family close to them this week.
The Prince of Wales, 40, and the Duke of Sussex, 38, have jointly signed a letter praising the work of a charity they both support and honor a family “that we all love and adore”.
Their message reached the annual fundraising service for the Henry van Straubenzee Memorial Fund, a non-profit organization set up by the parents, Alex and Claire, and siblings of their late friend, Henry van Straubenzee.
The royal brothers are patrons of the charity and have been attendees – and speakers – along with their wives, Kate Middleton and Meghan Markle, at the festive event in the past.
The charity supports schools and helps build, restore and improve buildings, enabling children to have better and better equipped classrooms and facilities such as toilets. When he died in a car accident in 2002, Henry had to travel to Uganda to work in a school during his gap year.
Kirsty O’Connor/AP/Shutterstock Prince William, Kate Middleton, Prince Harry and Meghan Markle at Windsor Castle
RELATED: Kate Middleton wearing Princess Diana’s emerald choker (once worn as a sash!) at the Earthshot Awards
Henry’s brothers Thomas and Charlie remain close to the princes and are godparents to William’s daughter Princess Charlotte and Harry’s son Archie respectively.
The letter signed jointly by William and Harry was brought in the order of service at Thursday’s carol service, which was attended by close friends, including Princess Kate’s sister and brother, Pippa and James, and their spouses, in St. Luke’s Church, Sydney Street, Chelsea.
Indigo/Getty Prince Harry and Prince William in happier times in 2011
Together, the princes wrote: “We believe everyone here tonight will agree that what Claire and Alex have been building since 2009… schools in rural Uganda where 1,700 projects have been completed and over 35,000 children , every year, they benefit from an education that they otherwise would not have had”.
“For those of us who knew Henners, we will always miss his mischievous charm and hilarious sense of humor,” they continued.
And although the brothers noted that the charity will gradually be scaled down, the letter nonetheless states that “Henry’s legacy will live on through the incredible accomplishments of what his mother and father have accomplished over the years.”
Wishing everyone a “pleasant evening and a merry Christmas,” the letter concluded: “As long as funds permit, they will continue to monitor their schools, enduring that the children of southeastern Uganda receive that vital education, providing an opportunity to escape poverty as they grow up and hopefully that of their children in the future. Thank you for your continued support in making this possible and for the undying support of the Van family who we all love and adore.” .
ANGELA WEISS/AFP Kate Middleton and Prince William
I just can not get enough PEOPLEthe coverage of Royals? Sign up for our free Royals newsletter to receive the latest updates Kate Middleton, Megan Markle and more!
The princes could not be at the carol service in person for several reasons.
William and Kate, 40, returned to Britain on Saturday morning following their three-day trip to Boston, which concluded with a triumphant Earthshot Prize ceremony at Fenway’s MGM Grand.
Harry, meanwhile, was in California, where he lives with Meghan, 41, and their children, son Archie, 3, and daughter Lilibet Diana, 1.
