"Grief is the most painful experience that any child or parent can endure" Prince William opens up about losing his mother .

Prince William spoke of losing his mother in a moving address at a dinner in Whitehall for the 21st anniversary of Child Bereavement UK (CBUK). The Duke of Cambridge, who was 15 when Princess Diana was killed in a Paris car crash told the charity, which supports families experiencing bereavement, that his mother would be “immensely proud” of their work.

He praised volunteers and staff for the “enormous, positive difference” they made to the parents and children supported by the charity, of which he is a patron, and said he understood their importance even more now he is a father of two.

He said the organisation “embraces strangers at the darkest moments in their life”. The charity was first launched in 1994 with Diana as a keen supporter and William said his mother had recognised the grief losing a child can cause.

"Twenty-one years ago last month, my mother attended the launch of the Child Bereavement Charity. 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. "CBUK works with military families, with the wrecked families of suicide victims, with little children whose lives have been 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."