Baby Boy Royal Family: Prince William and his wife Catherine, present their newborn son to the world.

 The world has seen the royal baby for the first time as the future king left hospital with his ecstatic parents this evening, who revealed they had not yet chosen him a name.

Prince William and Kate waved and smiled broadly to the waiting cameras as they held their prince on the steps of the private Lindo Wing at St Mary's Hospital in London, 26 hours after he was delivered, weighing 8lbs 6oz.

An obviously moved Duchess of Cambridge said: 'It's been very emotional. Any parent will know what this feeling is like.'

The Duke of Cambridge had followed the steps his parents Charles and Diana took with him 31 years ago, when he was born there on June 21, 1982.

'He's a big boy, quite heavy. We're still working on a name,' he told reporters.

'Well he has a good pair of lungs on him, that's for sure’

Confirming that the prince was overdue, William said: ‘I will remind him of his tardiness when he is older.’

With a huge smile he then added: ‘He’s got her looks thankfully’ to which the Duchess responded ‘No, no, no I’m not sure about that.’

Their child is now third in the line of succession, displacing Prince Harry to fourth and the Duke of York to fifth, although he may not become sovereign for half a century or more.

The Duke, Duchess and Baby Cambridge will travel home to Kensington Palace tonight, spending two weeks there while William is on paternity leave.

Huge crowds of well-wishers and journalists from all over the world have been waiting outside the west London hospital ward for weeks, first to be there when Kate went into labour and now as the couple left with her firstborn child.