The couple had earlier received their first visitors with heir to the throne Prince Charles and Kate’s parents Michael and Carole Middleton – all first-time grandparents – turning up at the hospital.
Congratulations have poured in from around the globe for the baby, a great-grandchild of Queen Elizabeth II, who will one day reign over Britain and 15 other Commonwealth realms around the world.
The baby remains officially nameless, although bookmakers have picked George and James – traditional names that hark back to previous kings – as favourites.
Cannon fire salutes rang out at the Tower of London and Green Park in celebration of the birth, while the bells at the 11th century Westminster Abbey pealed across the capital for three hours.
By mid-afternoon, Kate was well enough for a visit from her parents, self-made millionaires who run a party supplies business. They arrived in a humble black London taxi and initially looked bewildered by the sheer scale of the international media presence.
“He’s absolutely beautiful. They’re both doing very well and we’re so thrilled,” a beaming Carole Middleton told the media when she had recovered her bearings.
Charles arrived around two hours later with his wife Camilla in a chauffeur-driven limousine.
“Marvellous, thank you very much, absolutely wonderful,” said Charles, who earlier in the day had been on a tour of Yorkshire in northern England.
Hordes of journalists had camped outside the hospital for three weeks waiting for the baby, testament to the enduring appeal of the British monarchy and particularly the glamorous William and Kate.