Princess Diana was "open and authentic" according to her friend Julia Samuel.

Princess Diana

Princess Diana

The late royal had her life tragically cut short in 1997 when she was involved in a fatal car crash in Paris at the age of 36, and her close friend and grief psychologist Julia has now said the worldwide mourning of the blonde beauty came as "everybody felt they knew her".

Julia said: "There was something about her openness and authenticity -- everybody felt they knew her, and they felt they had a version of her inside themselves."

The 57-year-old psychotherapist is the founding patron of bereavement charity Child Bereavement UK, and has also opened up about the "misunderstanding and ignorance" surrounding grief.

She told People magazine: "There is so much misunderstanding and ignorance around grief, and that generates fear -- so that when people are bereaved, they don't know what to expect and how to support themselves.

"Pain is the agent of change. The thing that you don't want to feel is actually what you have to find a way of supporting. It's through allowing yourself to feel the pain that you heal, because it forces you to realise that this person has died, that your reality is altered."

Julia's work comes as Princess Diana's eldest son, 34-year-old Prince William, recently visited a centre run by the charity - which aims to help families struggling with the loss of a child, or to help children facing their own bereavements - to speak candidly about his own mother's passing.

Prince William, who is the older brother of Prince Harry, was filmed comforting a nine-year-old girl - who had recently lost her father - by explaining that he "lost [his] mummy when [he] was very young too."

Speaking to the girl, who was named as Aoife, Prince William said: "Do you know what happened to me? You know I lost my mummy when I was very young too. I was 15 and my brother was 12. So we lost our mummy when we were young as well."