"Do you speak about your daddy?" William asked the girl. "It’s very important to talk about it. Very, very important.”
William is royal patron of the Child Bereavement U.K. Centre, a charity that helps families deal with the loss of a loved one.
Aoife’s mother, Marie, spoke to journalists after the event and said the conversation almost brought her to tears.
“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,” she said.
William and Kate met with children at the facility in Stratford today and encouraged them to create memory jars to help them deal with their grief.
William admitted to the children he was very angry about his own mother's death.
“He told us how he felt angry when she died. He very specifically used that word anger, he felt angry about it," another mother named Lorna said of William’s interaction with the children. "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.”
“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.”
William and Harry are commemorating the 20th anniversary of the late Princess Diana's death later this summer.
Princess Kate: 'Parenting Is Tough'
The Duchess of Cambridge accompanied William to the engagement in a royal blue coat dress by the designer Eponine.
Earlier in the day, Kate attended her first engagement of the new year. The young mother stopped by the Anna Freud National Centre for Children and Families’ early years parenting unit and met with young mothers who have had to overcome family life battling addiction and abuse.
Kate encouraged the women, conceding "parenting is tough" no matter who you are or the circumstances you encounter while raising children.
Kate also visited with young mothers of children struggling with personality disorders and mental health challenges and commended them for their work.
"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," Kate said. "I find it extraordinary how you've managed actually. So really well done.”