The historic reform overturns a 300-year rule stating that first-born sons inherit the British throne. The only way for a woman to ascend to the throne, as Queen Elizabeth did in 1952, had been if the previous monarch had no sons.
The Commonwealth leaders also scrapped the rule barring a potential monarch from marrying a Catholic, although the monarch will remain head of the non-Catholic Church of England.
The changes mean that, regardless of gender, any first-born child of Prince William, second in line to become king after his father, would eventually become the monarch.
“If the royal couple have a girl rather than a boy, then that little girl would be our queen,” British Prime Minister David Cameron told the BBC. “This is a simple act of modernization and one that is right for our time.”
The reforms were announced in Perth, Australia, at a Commonwealth Heads of Government Meeting. Any of the Commonwealth countries could have vetoed the changes, but they were approved unanimously.
“The great strength of our constitutional approach is its ability to evolve,” Cameron said. “Attitudes have changed fundamentally over the centuries, and some of the outdated rules, like some of the rules of succession, just don’t make sense to us any more.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,” Cameron added.
But while the changes have been agreed upon in principle, individual governments, including those in Canada and Australia, must introduce legislation to enact them. A working group chaired by New Zealand will help to oversee the implementation of the changes.
“Obviously, it’s important that the monarchy reflects the times,” said Robert Lacey, a royal biographer. “As someone once said about the queen, ‘Everything changes but the headscarf.’ ”
Lacey said it was “wonderful that all the Commonwealth heads of state are discussing this. . . . It’s a great tribute to the queen and the way she has run the monarchy, and it shows it all still matters in people’s hearts.”
The rules are not retroactive, so the current succession rankings do not have to be rearranged.
Queen Elizabeth’s second child, Princess Anne, remains 10th in line to the throne, well behind the queen’s third child, Prince Andrew. Andrew is fourth in line, behind his brother Charles and his nephews, William and Harry.
But scholars are already reaching back into time and hypothesizing about how such royal gender equality would have affected history.
During the Tudor dynasty, for example, the passionately Protestant King Edward VI would not have ascended the throne, because his older half-sister Mary would have been heir. Without a King Edward, Lacey said, “it’s possible to say that Britain might still be Catholic. These things are not inconsequential.”