The Duke of Cambridge's uncle, Earl Spencer, described his joy at the new royal baby.
"We're all so pleased: it's wonderful news," he said.
The Earl, whose sister was the Duke's mother, Diana, Princess of Wales, added: "My father always told us how Diana was born on just such a blisteringly hot day, at Sandringham, in July 1961. It's another very happy summer's day, half a century on."
The Duke and Duchess of Cambridge proudly showed the world their baby son, a future king, before taking him home tonight.
The royal baby appeared to wave as he was introduced to the crowds outside the hospital for the first time.
It's been revealed the new Royal parents and their new son will be making a family home at Anmer on the Sandringham Estate in Norfolk.