Prince William movingly comforted a little girl grieving for her father today, telling her: "I lost my mummy when I was very young too."
The prince, who later this year will mark the 20th anniversary of the death of Diana, Princess of Wales, asked Aoife, nine: "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."
The prince, accompanied by his wife, the Duchess of Cambridge, was visiting the Child Bereavement UK Centre in Stratford, which is marking its one year anniversary, and provides support for children and families when a baby or child of any age dies or is dying, or when a child is facing personal loss, the Daily Mail reports.
He urged Aoife, whose father John died from pancreatic cancer six years ago, not to bottle up her loss, adding: "Do you speak about your daddy? It's very important to talk about it. Very, very important."
Aoife's mother, Marie, said afterwards: "I couldn't believe it when he started to talk about his mother. It was very emotional and I was willing myself not to start to cry. I almost did.
"I am telling my children that if they take anything away from this day, it is what he said about how important it is to talk. Kids do not forget that.
"Sometimes it hurts but we can remember the happy things too. It is so important to talk."
As Royal Patron of Child Bereavement UK since 2009, William has long supported the vital work undertaken by the charity, which makes such a positive difference to bereaved families across the country.
The charity also provides training for 8,000 professionals a year whose work brings them into contact with bereaved families.
Child Bereavement UK was established in 1994 in the presence of Diana, Princess of Wales, whose best friend, Julia Samuel, is Founder Patron of the organisation. Samuel has remained close to William and was asked to be Prince George's god-mother.
On arrival at the centre William and Kate were given a briefing about the work of the charity before sitting in on a session where a group of youngsters were making "memory jars".
The jars were filled with tightly packed layers of multi-coloured salts, each colour representing a memory of their loved one.
William sat down with Aoife, nine, and her brother Keenan, 12. They lost their father John to pancreatic cancer six years ago tomorrow.
William knelt down to chat with the youngsters and told Aoife about his own personal experience at losing his mother, before turning to her mother, Marie, to discuss the importance of talking about the person they have lost.
William said: 'I think that for children it is sometimes difficult to understand that. '
He asked of Marie: "Are there family or friends that can keep an eye on you too? That's important, too, you know."
Marie, from Redbridge, said afterwards: "Pancreatic cancer is very aggressive and difficult to diagnose and John didn't fit the bill at all - he was young, healthy and ate well.
"We lost him very quickly after he was finally diagnosed. My children were almost six and three. My son wanted to talk about it but my daughter was finding it very hard and didn't want to.
"It took my a long time to find Child Bereavement UK, we have been working with them since June, but what they have done for us as a family has been remarkable.
"Aoife didn't want to sit down with a counsellor one-on-one, but they work there with activities, enabling her to discuss her feelings in a more relaxed way.
"And it has helped me enormously too. Tomorrow is the sixth anniversary to losing my husband.To be honest it will be just another day for us. It's the moments that you don't expect when it hits you. Like when you used to sit down and watch the TV together in companionable solitude."
Aoife said she told William that she had chosen bright colours - reds, yellow, pinks and greens - for her memory jar because her father liked bright colours and loved gardening.
"It was really nice that he talked to me. It was like there are other people who know what it is like to lose someone."
Indeed, William has previously opened up about his grief at losing his mother Princess Diana in a car crash in 1996.
"Never being able to say the word 'Mummy' again in your life sounds like a small thing," he said. "Life is altered as you know it, and not a day goes past without you thinking about the one you have lost."
He added: "I know that over time it is possible to learn to live with what has happened and, with the passing of years, to retain or rediscover cherished memories."
William was joined on the engagement by his wife Kate, who wore a £1,650 (NZ$2,850) blue Eponine cost dress and also showcased a subtle style tweak by wearing her tendrils of her brunette hair swept back and held in place with mini bulldog clips.
He also spoke to Shinobi, 12, who had earlier presented Kate with a bouquet of flowers, who had lost his grandmother three and half years earlier.
His mother, Lorna, had thought he was coping, but later heard from his school that he was finding her death difficult to cope with.
She said William also talked about losing his mother to them - and how much anger he felt at the time.
"He told us how he felt angry when she died. He very specifically used that word anger, he felt angry about it. He also told us how important it was to talk about how we feel when we lose someone as he found it very difficult to talk about it," she said.
"I was very touched that he wanted to speak to us about.
"We also spoke to the Duchess who told us that it was ok to feel the way we are feeling. That we shouldn't be afraid to feel sad."
Kate also spoke with several children and their families as they prepared the coloured salt to pour into their memory jars.
She asked one little girl: "What colours have you chosen? Does that make you remember something about your father? It's really lovely that you can talk about things with your friends at school."
Speaking after the event, Julia Samuel, who has known William sine he was born and greeted both him and Kate with a warm kiss, praised the prince for his openness.
"William has great depth of understanding in a way that you never expect from such a public figure and yet he is also so friendly and funny," she said.
"You can see when people meet him that their eyes widen a little when they recognise him but when he talks to them about what has happened to them and himself, then he very quickly becomes a human being.
"I don't think any of us can even begin to understand what he and Harry went through. Their mother's death was such a public event and yet they were feeling such a depth of personal grief.
"What they have both learnt and are so keen to get across, however, is that talking about your grief at the earliest possible stage is so important. The earlier we talk about these things, the less harm is done."
She added: "What William is bringing to our charity is just immeasurable. He has lived and breathed what these families are experiencing. He is really involved as a patron and believes in the service we can offer.
"Grief is an invisible wound, people don't know what you are suffering, they don't offer you a chair to sit on because you look ill.
"But William knows and recognises this and I think people respond to this.
"Bereavement - particularly the death of a child - is unbearable to think about and he is something he's shining a light on and helping us raise awareness of the need of people who have children who die in the way that no one else can do.
"That's because people can see how authentic, and heartfelt, he is and he's experienced it. People can pick up authenticity within seconds."
While at the Stratford site, the royals were introduced to local professionals, and volunteers who work at the service, before meeting families and children who have been supported by the charity.
They then attended one of the charity's Family Support Group sessions where children, their parents, and carers can meet other families to explore themes of memories, feelings, support networks and resilience.
These sessions can help to decrease their sense of being alone and feeling "different" when someone important in their lives has died.
The engagement closed with a short reception to mark the Stratford Centre's first anniversary where William cut the birthday cake in front of staff, volunteers, users of the service and donors.
Their visit is Kate's second engagement of the day, after visiting an early years centre run by the Anna Freud National Centre for Children and Families in Finsbury Park earlier.
And the Duchess admitted "parenting is tough" as she met young mothers battling emotional problems today at the Anna Freud Centre in London.
She may have a full-time live-in nanny and a mother who gives her plenty of help with Prince George, three, and Princess Charlotte, 20 months, but Kate, 35, suggested it still wasn't easy bringing up a family after listening to the stories of a group of mother who have been through problems such as a family history of abuse and addiction
"Parenting is tough," she said. "And with the history and all the things and the experiences you've all witnessed, to do that on top of your own anxieties, and the lack of support you also received as mothers...I find it extraordinary how you've managed actually. So really well done."
Kate was asked if she was braced to spend the morning with a group of children under five at a centre that helps parents with personality disorders bond more closely with their offspring.
"I did just leave a room of six under threes," she said, smiling.
It was not clear if Princess Charlotte, who will be two in May, had got friends over on a play date or whether Kate was referring to having pals with their own children to stay as they celebrated her 35th birthday on Monday back at their country home, Anmer Hall in Norfolk.
She visited the unit to learn more about its work with families who have children under five that are at risk of being taken into care.
She heard one mother describe how she had been trafficked from Nigeria and had not wanted her son, now six, when she was pregnant but now had a much improved relationship after coming for treatment when he was three.
"I got depressed really badly," she said. "I needed help because I was trafficked to this country."
Kate listened to another mother, who had her first baby when she was 17, describe how she had her first four children taken away from her because she came from a 'really bad family' and had no support.
Later she met parents taking part in a "theraplay" session that helps the child-parent relationship.
She demonstrated her maternal side as she entertained 18-month-old Le'Jaun with smiles and waves during the session.
"What's this strange woman?" his mother, Amber, 19, said, as he stared at the Duchess.
Amber has been receiving treatment at the centre for four months to help her cope with anxiety attacks.
"I don't think the work that is done here is publicised enough," Amber said, praising the help she has received.
It was the latest in a series of royal engagements for the Duchess designed to draw attention to child mental health issues. She is a champion of early intervention and working with the whole family to resolve problems with children.
The unit in Holloway opened in April 2011 and offers an assessment and treatment programme for groups of parents with personality disorders, and their children under five, who are at risk of being taken into care.
The treatment aims to address the parents' personality disorders - often the result of abuse, trauma and addiction in their families - help deal with the children's developmental needs, and improve the parent-child relationship.
Staff at the centre try ultimately to keep families together and help parents become more aware of and responsive to their children's needs.
Later Kate met privately with families who have benefited from another of the centre's early years service, Parent Infant Psychotherapy (PIP).
The PIP service supports expecting and new parents, advising them about the impact of a new baby.
It was the Duchess' second visit to the Anna Freud National Centre for Children and Families since she became patron in May last year.
Peter Fonagy, chief executive of the Anna Freud Centre, said: "The Duchess is stimulating interest in similar services throughout the country and right across the world."