An easel stands in the forecourt of Buckingham Palace in London on July 22, 2013, to announce the birth of a baby boy, at 4.24pm to Prince William and Catherine, Duchess of Cambridge, at St Mary's Hospital. Prince William's wife Kate on Monday gave birth to a baby boy who will one day be heir to the British throne, Kensington Palace said in a statement. AFP PHOTO / JOHN STILLWELL/POOL (Photo credit should read JOHN STILLWELL/AFP/Getty Images)

An easel stands in the forecourt of Buckingham Palace in London on July 22, 2013, to announce the birth of a baby  boy, at 4.24pm to Prince William and Catherine, Duchess of Cambridge, at St Mary's Hospital. Prince William's wife Kate on Monday gave birth to a baby boy who will one day be heir to the British throne, Kensington Palace said in a statement.  AFP PHOTO / JOHN STILLWELL/POOL        (Photo credit should read JOHN STILLWELL/AFP/Getty Images)