London, July 23: Congratulatory messages poured in as Prince William's wife Kate Middleton today gave birth to a baby boy, with the whole of Britain and the Royal family ecstatic at the arrival of the country's future King.The 31-year-old Duchess of Cambridge gave birth to a baby boy this evening at 16:24 (local time), Kensington Palace said in a statement."Her Royal Highness The Duchess of Cambridge was safely delivered of a son," said the statement. "The baby weighs 8lbs 6oz. (3.8 kilos)."British Prime Minister David Cameron was among the first to take to Twitter to say: "I'm delighted for the Duke and Duchess now their son has been born. The whole country will celebrate. They'll make wonderful parents".Prince Charles, the grandfather of the 8lbs 6oz boy, reacted by saying he was "enormously proud and happy". "Both my wife and I are overjoyed at the arrival of my first grandchild. It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy," he said soon after the official announcement."Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months, so I am enormously proud and happy to be a grandfather for the first time and we are eagerly looking forward to seeing the baby in the near future," Charles said.Queen Elizabeth II is expected to have been the first to be informed about her newest great-grandson by phone.She will be heading off to Balmoral Castle for her annual summer break soon and had said she wanted the baby to "hurry up and arrive" before she was to leave London.The statement issued by Kensington Palace, the Duke and Duchess' official residence, confirmed that William was present for the birth."The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry and members of both families have been informed and are delighted with the news," the statement said.The name of the baby will be announced in due course, it added.