Prince William, has said "grief is the most painful experience that any child or parent can endure."
The Duke of Cambridge, who was 15 when his mother, Princess Diana was killed in a car crash, spoke about his mother and children during a speech at a dinner to mark the 21st anniversary of Child Bereavement UK (CBUK), a charity his mother helped to launch and he is now patron of.
"CBUK's humanity is simply unparalleled, and it is deeply moving," he said.
"As a father to two young children, I now appreciate it all the more."
"Twenty one years ago last month, my mother attended the launch of the Child Bereavement Charity," the Duke said.
"Fifteen years later, I was honoured to be invited to become patron of Child Bereavement UK to continue my mother's commitment to a charity which is very dear to me.
“What my mother recognised back then – and what I understand now – is that grief is the most painful experience that any child or parent can endure.
"But my mother was determined to help those in need and she would have been immensely proud – as I am – of all that Child Bereavement UK has achieved these last 21 years.”
Princess Diana with six-month-old Prince William on 22 December 1982
"Tonight we celebrate the enormous, positive difference this charity has made to bereaved families across the country," William continued.
"When many people slink away at the sight of a friend's bereavement, CBUK's staff embrace strangers at the darkest moment in their life.
"I have witnessed first-hand the difference CBUK has made – and continues to make – to the lives of bereaved families.
"CBUK works with military families, with the wrecked families of suicide victims, with little children whose lives are torn apart by the inexplicable death of a parent.
"And yet amid all this misery, CBUK – and I don't know how they do this – brings warmth, comfort, a guiding hand, a way through, even colour and joyfulness, and a renewed opportunity for love as a family reknits itself after tragedy."
CBUK’s founder patron Julia Samuel was one of Princess Diana's best friends and is now godmother to Prince George.
Prince William, Duke of Cambridge, Prince George of Cambridge, Catherine, Duchess of Cambridge, Princess Charlotte of Cambridge and and Queen Elizabeth II pose in front of (L-R) Michael Middleton, Pippa Middleton, James Middleton, Carole Middleton, Prince Charles, Prince of Wales, Camilla, Duchess of Cornwall and the Duke of Edinburgh pose for a family photo after the christening of Princess Charlotte of Cambridge at the Sandringham Estate on July 5, 2015 in King's Lynn, England.
Child Bereavement UK supports families when a baby or child dies or is dying, or when a child is facing bereavement. It trains almost 7,000 professionals every year, to help them better understand and meet the needs of grieving families.
Another of the charity's high profile supporters charity’s supporters, Gary Barlow performed at the event.
The Take That singer and his wife Dawn's baby daughter, Poppy, was stillborn in 2012.
"Dawn and I have always felt our own personal bereavement was too painful and private to talk or comment on publicly," said Gary before he took to the stage.
"Instead I will sing joyous music in support of Child Bereavement UK to say thank you for all the help it has given us and many other families."