Prince Harry has declared he is ready to play the proud, protective uncle for his new nephew 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 on Thursday night documenting the work of his Africa-based charity Sentebale.
Asked what he would do as an uncle, he said: "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 on Wednesday as George Alexander Louis – Prince George of Cambridge.
The baby is destined to become George VII if his grandfather, Prince Charles, and father William choose to use their first names when they become monarchs, and not a middle name.
George's name is thought to be in tribute to the Queen's father, King George VI. Harry 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."
When asked what his nephew was like, Harry held up his hands and said: "Well he's about that long and about that wide." He added: "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 William was up to the job of fatherhood, he replied: "Of course he is. Hopefully most people are."
The prince had spent around half an hour viewing the exhibition Sentebale - Stories of Hope at the Getty Images Gallery in central London.
Some of the pictures were taken in February during the royal's trip to the southern African kingdom of Lesotho, where his charity supports a range of projects that help disadvantaged children and young people.
Sentebale, which means Forget Me Not in the local language, was founded in 2006 by Prince Harry and Prince Seeiso of Lesotho, and has improved the lives of thousands of children by providing healthcare and education to those most in need, including children orphaned by the country's HIV/Aids epidemic.