Catholics to be allowed into the royal club (sort of)

London (CNN)— Britain is about to change a 300-year-old rule. British kings and queens – who serve as the official leaders of the Church of England – will soon be allowed to marry Roman Catholics. The historic change will end a centuries-long ban on such interdenominational nuptials.

British Prime Minister David Cameron announced plans last year to change the law, along with another historic amendment – the end of primogeniture, which says that males come ahead of their sisters in the order of succession, no matter who’s older.

It is a move that could affect the younger royals, including the newest member of the royal family, the baby that Prince William and Catherine, Duchess of Cambridge, are expecting next year.

While the new amendment allows for kings or queens to marry Catholics, the monarchs themselves can't be Catholic, because by definition the king or queen is the head of the Church of England.

This new legislation would mark a monumental shift in religious relations with the Catholic Church in England.

Exclusion and persecution of Roman Catholics began with King Henry VIII’s rejection of papal supremacy in 1534 with the Act of Supremacy.

This act established the English monarch as the supreme head of the Church of England and severed relations with the Vatican. Under Henry’s son, Edward VI, the Church of England moved further toward Protestantism with the publication of the Common Book of Prayer and the abolition of the Catholic Mass. Edward was then succeeded by his Catholic half-sister Mary I (aka “Bloody Mary”), who shifted England back to a nation aligned with the Vatican.

After Mary’s death, her half-sister Elizabeth I took control of the throne and returned England to Protestantism. The last Roman Catholic monarch of England was James II, who ruled from 1685 to 1688, when he was overthrown during the Glorious Revolution.

The narrative of conspiracy and violence between Protestants and Catholics continued through the next hundred years, leaving practicing Roman Catholics marginalized at best and brutalized at worst.

England began to roll back restrictions on Catholics during the 19th century. Most notably, the Roman Catholic Relief Act of 1829 permitted members of the Catholic Church to sit in the parliament at Westminster. Yet until now, no British monarch could marry a Catholic.

The new legislation announced by Cameron would amend the Bill of Rights and Coronation Oath Act of 1688, the 1701 Act of Settlement and the 1706 Act of Union with Scotland. The various pieces of law explicitly disqualify anyone who becomes a Roman Catholic, or who marries a Roman Catholic, from inheriting the throne.

So what comes next? Deputy Prime Minister Nick Clegg said in a statement on Tuesday that all 16 realms of the Commonwealth have consented to the landmark bill and that the government will “seek to introduce the Succession to the Crown Bill in the House of Commons at the earliest opportunity allowed by the parliamentary timetable.”

Vincent Nichols, archbishop of Westminster and president of the Catholic Bishops’ Conference of England and Wales, lauded the move.

"This will eliminate a point of unjust discrimination against Catholics and will be welcomed not only by Catholics but far more widely,” Nichols said in a statement.

But he acknowledged the role of the Church of England, saying, “At the same time I fully recognize the importance of the position of the Established Church in protecting and fostering the role of faith in our society today.”

Historian and writer Antonia Fraser said the government was doing the right thing.

“The Catholic question has not really occurred in terms of the heir (before). It’s not to say that it wouldn’t occur, and I think that if they are altering things it’s a good idea because it is a slur on Catholics … and I think they are right to alter it.”