Successors to the throne

The U.K. Parliament regulates the line of succession to the British throne, using guidelines laid out in the Bill of Rights (1689) and the Act of Settlement (1701).

In October 2011, Commonwealth leaders unanimously agreed to remove the centuries-old gender discrimination rule that favours first-born sons over older daughters in the order of succession to the throne.

Prince William, second in line to the throne, and his wife, Kate, the Duchess of Cambridge, announced Dec. 3 that they are expecting their first child in 2013. The gender of the child is not known.

While the new law has not yet been introduced in the British Parliament, it's already de facto law, says a spokesperson for the British Cabinet Office.

If William and Kate's first child is a girl, she will be able to succeed the throne, no matter if she eventually has a younger brother.

"Even though the bill hasn't actually been introduced here yet that doesn't matter. It's effectively law already," the cabinet office spokesperson said.

The cabinet office hopes to introduce a bill very soon, the spokesperson said. 

The move came after British Prime Minister David Cameron sent a letter to Commonwealth leaders — including Prime Minister Stephen Harper — proposing to change British law so that a male heir no longer takes precedence over a female heir.

The Commonwealth leaders also agreed to lift a ban on the monarch being married to a Roman Catholic.

According to the Act of Settlement, only Protestant members of the Royal Family who are descendants of Princess Sophia (1630-1714), the Electress of Hanover, a granddaughter of James I, can be considered for the throne.

The sovereign is required to take an oath to defend the Church of England and the Church of Scotland. A Roman Catholic is disqualified from succession to the throne.

There are more than 900 people in line for the British throne; the first 510 on the list are descended from Queen Victoria (1819-1901).

Rules specifying who inherits the throne, now based on the 1701 Act of Settlement, are not easy to change — particularly because they involve all 16 Commonwealth countries where Queen Elizabeth is head of state.

Harper has said the "obvious modernizations" were long overdue. He hasn't given a timeline for when legislation will come before Parliament for approval, but said he hopes it will be adopted quickly.