According to journalist Rhiannon Mills, Prince Harry's reaction to her question left her 'gobsmacked.'
"What was amazing about that conversation was how down to earth he was. How candid he was," Ms Mills told podcast Behind the Royals.
Recalling the first time she was ever allowed to speak to the Duke, Ms Mills reveals how she asked him about the birth of his niece, Princess Charlotte.
"I said to him: 'Oh, you were away for the birth of Princess Charlotte. Did you feel that you missed out on this big moment for your brother and sister in law?'
"And he turned around to me and said: 'Look when you've been in the Army and when you lost your mother at the age that I did, you toughen up'.
"And I just thought wow, that is quite something to be said in the very first conversation I had ever had with him."
Ms Mills continued: "...It gave me an insight into the kind of man that he was in that he will be very open."
Prince Harry welcomed his first child with Meghan Markle on May 6, 2019.