The Government has received consent from the Commonwealth realms to press ahead with legislation to change the laws of succession to the British crown.
The legislation will end the practice of men taking precedence over women in line to the throne, and end the bar on anyone in the line of succession marrying a Roman Catholic.
Deputy Prime Minister Nick Clegg called the step a "historic moment".
It is a wonderful coincidence that the final confirmation from the other realms arrived on the very day that the Duke and Duchess of Cambridge made their announcement.
The Government will soon introduce the Succession to the Crown Bill which will make our old fashioned rules fit for the 21st Century.
It will write down in law what we agreed back in 2011 – that if the Duke and Duchess Cambridge have a baby girl, she can one day be our Queen even if she later has younger brothers.
The Duchess of Cambridge left hospital today, after three days of treatment for a severe form of morning sickness.
A nurse disclosed information about Kate's condition to two DJs who rang the hospital claiming to be the Queen and Prince Charles.
The Duchess of Cambridge is to spend another night in hospital being treated for acute morning sickness but is said to be feeling better.