While at the gallery, where he was on hand for the launch of an exhibit by photographer Chris Jackson that showcases Harry's charity, Sentebale, he talked about meeting Kate Middleton and Prince William's bundle of joy for the first time.
"It's fantastic to have another addition to the family," Harry told the crowd, before quipping, "I only hope my brother knows how expensive my baby sitting charges are!"
He kindly added that, as George's uncle, he wants "to make sure he has a good upbringing and to keep him out of harm's way and make sure he has fun. The rest of it I'll leave to the parents."
Tune in to the E! News special, A Royal Family, tonight at 8 p.m. PT