Prince Harry has declared he is ready to play the proud, protective uncle for his new nephew Prince George and "make sure he has fun".
Harry could not stop beaming as he talked about the newest member of his family during his visit to a photographic exhibition in London documenting the work of his Africa-based charity Sentebale.
Asked what his mission was as an uncle, the royal replied: "To make sure he has a good upbringing, and keep him out of harm's way and to make sure he has fun. The rest I'll leave to the parents."
Harry said he had already cuddled the Duke and Duchess of Cambridge's baby, who was born on Monday and named George Alexander Louis - Prince George of Cambridge.
The baby is destined to become George VII if his grandfather (the Prince of Wales) and his father William choose to use their first names (not a middle name) when they become monarchs.
The infant prince's name is thought to be in tribute to the Queen's father, King George VI.
The 28-year-old prince said: "When I saw him he was crying his eyes out like all babies do I suppose - it's fantastic to have another addition to the family. I only hope my brother knows how expensive my babysitting charges are."
Ever the joker, when asked what his nephew was like he held up his hands and said: "Well he's about that long and about that wide."
Harry said it was too early to say whether Prince George takes after any member of the family, as: "He is about four days old so I think you can judge that one for yourself. I've no idea."
And when he was asked whether Prince William was up to the job of fatherhood, he replied: "Of course he is. Hopefully most people are."