The Duke of Sussex, who is currently in the Hague for the Invictus Games, has said he is not yet sure whether he or his family will attend the celebration in June.
The royal, along with his wife Meghan, made a brief pit-stop at Windsor Castle to visit the Queen while on their way to the Games last week.
However, the couple’s two children stayed at their home in California.
The monarch met Archie as a newborn baby before Meghan and Harry moved to the US, but she has yet to meet 10-month-old Lilibet – who was named after the Queen’s nickname.
When speaking during an interview while at the Games, Harry said he is “trying to make it possible” for his children to meet their great grandmother.
He said: “So this is what I’m trying to do, trying to make it possible that I can get my kids to meet her [the Queen].”
The Duke had kind words to say about his grandmother and his brief visit to the Castle, saying it had been “really nice to see her” while they had “an element of privacy”.
He said: “It was so nice to see her – she was on great form.
“She’s always got a great sense of humour with me and I’m just making sure she’s protected and has got the right people around her”.
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The Duke also spoke warmly about Diana, Princess of Wales, saying he speaks to his son about her and believes she is watching over them.
He said: “It’s almost as though she’s done her bit with my brother, and now she’s very much helping me get set up. He’s got his kids, I’ve got my kids.
“Circumstances are obviously different, but I feel her presence in almost everything that I do now, more so in the last two years than ever before”.
The Duke is still at the Invictus Games which he founded to aid the rehabilitation of injured or sick military service people and veterans by giving them the challenge of competing in sports.
He is expected to give a speech at the closing ceremony on Friday.