Women gain equal succession rights
Prince William's first child will follow him on to the throne whether it is a girl or a boy, after agreement was reached on historic constitutional changes to end gender discrimination in the rules of succession.
The 16 Commonwealth nations of which the Queen is monarch agreed unanimously to end the rule of primogeniture, under which a younger son takes precedence over older sisters in the order of succession.
The 16 "realms", including the UK, Australia and Canada, also agreed to scrap centuries-old laws which ban the spouse of a Roman Catholic from ascending to the throne.
Announcing the changes at a Commonwealth summit in Australia, Prime Minister David Cameron said the "outdated" rules were "at odds with the modern countries that we have become".
Explaining how the rules on succession will change, he said: "Put simply, if the Duke and Duchess of Cambridge were to have a little girl, that girl would one day be our queen."
Reform of the succession rules, which date back to the 17th century, has long been seen as overdue in an age of greater equality between genders and faiths.
Mr Cameron said: "Attitudes have changed fundamentally over the centuries and some of the out-dated rules - like some of the rules of succession - just don't make sense to us any more.
"The idea that a younger son should become monarch instead of an elder daughter simply because he is a man, or that a future monarch can marry someone of any faith except a Catholic - this way of thinking is at odds with the modern countries that we have become."
His announcement was welcomed by the head of Roman Catholics in England and Wales, Archbishop of Westminster Vincent Nichols, who said the reform would "eliminate a point of unjust discrimination against Catholics".
But Graham Smith, of the Republic campaign for an elected head of state, said: "The monarchy discriminates against every man, woman and child who isn't born into the Windsor family. To suggest that this has anything to do with equality is utterly absurd."