Kate Middleton, the Duchess of Cambridge, has given birth to a baby boy. The unnamed son is third in line to the throne. Both mother and child are doing well, Kensington Palace said in a short statement. They will both remain in hospital overnight.

The son of Prince William and Middleton weighed 8lbs 6oz (3.6kg). He was delivered at 4.24pm in the maternity wing of St Mary's hospital, London, by natural birth. The Duke of Cambridge was at the bedside.

'We could not be happier,' William said in a statement. A Buckingham palace spokesman said the Queen and Duke of Edinburgh are 'delighted at the news'. The prime minister, David Cameron, predicted William and Kate will 'make wonderful parents'.

Hundreds gathered outside the hospital to celebrate the news. The crowd sang: 'Happy birthday dear royal baby,' in absence of a name. Later several hundred people were outside Buckingham Palace, where an ornate easel announced the birth.

The birth of the royal baby had been followed around the world. In America rolling news channels devoted their coverage to the birth, while Australia prime minister Kevin Rudd sent his country's 'warmest regards' to the new family..