The duke, who is an ambassador for Scotty’s Little Soldiers, a charity for bereaved military children, discussed coping with grief with its founder Nikki Scott, whose husband Lee died on duty in 2009 .

A video has been released of Prince Harry comforting a mother as she opens up about the moment she had to tell her son his father had been killed in Afghanistan.

Ahead of Armed Forces Day on Saturday, the charity Scotty’s Little Soldiers, which supports bereaved military children, filmed the interview between its founder Nikki Scott and the Duke of Sussex, in which he also shares his own feelings about losing his mother.

In July 2009 Nikki was told her husband Corporal Lee Scott, who served with the 2nd Royal Tank Regiment had died, news she then had to share with five-year-old son, Kai, while also caring for their seven-month-old daughter, Brooke.

In a heartbreaking conversation with Harry she says: “It was the worst. How do you tell a five-year-old this?

Image:Cpl Scott with his wife Nikki and their children Kai (centre right) and Brooke before his deployment to Afghanistan Pic: Nikki Scott

“I took him up and sat him on the bed and I said, ‘Kai, do you remember where Daddy was?’ and he said, ‘yeah, Afghan‘, and I said, ‘something really bad has happened and the baddies (because he used to play army) have hurt dad and he’s died’.”

Bursting into tears she described the pain of “shattering her son’s world”.

Image:The body of Cpl Lee Scott arrives back in the UK, 14 July 2009 Pic: Ministry of Defence

Nikki’s personal tragedy inspired her to create Scotty’s Little Soldiers in 2010 to help other children. Prince Harry is the group’s global ambassador, and the conversation was filmed when he visited the UK and surprised children at a Scotty’s event in May.

In their chat, Nikki also refers to Harry’s experience of losing his mother Princess Diana when he was only 12, and how in his book Spare he talked about visiting the tunnel in Paris where she died.

Harry explained the complexity of dealing with his sense of loss, telling her: “You convince yourself that the person you’ve lost wants you, or you need to be sad for as long as possible to prove to them that they are missed.

“But then there’s this realisation of, no, they must want me to be happy.”

A huge advocate of the importance of discussing mental health, he said: “That’s the hardest thing, especially for kids, I think, which is, ‘I don’t want to talk about it because it will make me sad, but once realising if I do talk about it, and I’m celebrating their life, then actually, things become easier’.”

Scotty’s Little Soldiers currently supports over 680 children, but they estimate that each year 2,100 children are newly bereaved of a parent who served in the British Armed Forces.

To raise awareness of the ongoing need for help the charity has also recorded videos with some of the young people sharing their stories about their parents and “remembering their heroes” ahead of Armed Forces Day.