Speaking at a visit to a photography exhibition, Prince Harry – who has been bumped down to fourth in line to the throne by George's arrival – 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 baby sitting charges are!"
Asked about his most important role as uncle, he added: "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."
Baby George is currently staying at Kate's parents' house in Berkshire. The new family travelled to the country after spending one night at home at Kensington Palace.
Kate, William and George left for chez Middleton after the Queen, Harry, and Kate's siblings Pippa and James met the new member of the family soon after he left hospital.