Royal women to get equal rights

The changes mean that if the Duke and Duchess of Cambridge’s first child is a girl, she will take precedence over any younger brothers in the order of succession.

The 16 “realms”, including the UK, Canada and Australia, also agreed to scrap outdated laws which ban the spouse of a Roman Catholic from taking the throne.

The changes were announced by Prime Minister David Cameron at the Commonwealth Heads of Government Meeting, attended by the Queen, in Perth, Australia.

Mr Cameron said the historic rules were “at odds with the modern countries that we have become”.

Announcing the proposed changes, 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.”

Mr Cameron added: “The great strength of our constitutional approach is its ability to evolve.

“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.”

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.

But the pressure for change became more urgent following the marriage of Prince William and Catherine Middleton in April, which raised the prospect of new additions to the line of succession in the near future.

Putting future princesses on an equal footing with their brothers will require amendments to a raft of historic legislation, including the 1701 Act of Settlement and 1689 Bill of Rights, as well as laws in a number of the Queen’s other realms – Australia, New Zealand, Canada, Jamaica, Antigua and Barbuda, Belize, Papua New Guinea, St Christopher and Nevis, St Vincent and the Grenadines, Tuvalu, Barbados, Grenada, Solomon Islands, St Lucia and the Bahamas.

Any legislative changes will apply to the heirs of the Prince of Wales, so the children of William and Catherine will be affected whether or not they are born before the process of amending laws is completed.

Mr Cameron made clear that although heirs to the throne will in future be allowed to marry Roman Catholics, the ban on a Catholic becoming sovereign will remain, as the monarch is also the head of the Church of England.