According to the Beeb, the Commonwealth nations – more or less the successor to the British Empire and mostly made up for former British colonies, many of whom still have the King or Queen of England as their head of state – have agreed to change the succession rules for the throne, allowing the first-born child of either sex (rather than the first-born son) to inherit the throne in his or her own right.
Interestingly, they also undertook to allow the spouse of the future monarch to be Roman Catholic. This was banned under the Act of Settlement in 1701, which essentially cemented Parliament's role in confirming the and controlling the succession and gave legal backing to the overthrow of the Roman Catholic James VII & II* of the House of Stuart, and to the replacement of the (Catholic) House of Stuarts with the (Protestant) House of Hannover. It also ensured that future monarchs could never be Roman Catholic again, nor be influenced by their spouses, who might try to raise their children Catholic and therefore circumvent the law.
This has some significance for the Church of England and thus for all Anglicans. The reason is that the ruling monarch of England is also the supreme head of the Church of England, thanks to Henry VIII (as covered here and here). To clarify, however, the monarch is only the head of the C of E, not of all Anglicans, and while he or she influences the Communion as a whole by virtue of selecting the Archbishop of Canterbury, he (for now likely to only be a he) in practice merely chooses whomever the C of E in synod recommends.
The oddity of the law until now, however, was that in theory a future king or queen could have had a non-Anglican spouse – just not a Roman Catholic one. Atheist, Buddhist, Flying Spaghetti Monster, all these were possible, just not Papists. So in one sense it does clear up something that was difficult to justify in 1701, and is downright anachronistic today.
Just for a little Hannover-related trivia, this is why the current head of the House of Hannover, Prince Ernst August, disqualified himself from the succession by marrying Princess Caroline of Monaco, who is Roman Catholic. His children and younger brother still qualify and took his place in line. Since he was only 385th in line to the throne, I don't think he lost much sleep over it.
That said, in theory, there could now be a strange setup coming in the future – a future king or queen who is head of the Anglican church, but whose consort is Roman Catholic, poses legal problems as well. Roman Catholics are required to raise their children Roman Catholic as well, so even if a future Anglican monarch was not him or herself Roman Catholic, presumably the children would be. Then what? How could a Roman Catholic, or for that matter an atheist or Buddhist, be supreme head of the Church of England, Defender of the Faith** and all that?
I think the only logical solution to this legal issue, but also to resolve many others, is to disestablish the Church of England, that is, to no longer have it be the state church. You may be surprised by this, considering my discussion about the issues around Henry and his wives, but in the modern age, I am convinced that separation of church and state is not only rational and fairer to other religious (or non-religious) groups, it is also beneficial to the church in the long run.
I would argue that the strict separation of church and state in the US is one contributing factor to why religion is still so vibrant there compared to Europe. Admittedly, disestablishment would hurt the C of E in the short term – the loss of tax support, while presumably still having to pay the considerable costs of maintaining public buildings, like all those churches and cathedrals – in the long run I think it would healthy. An example can be found right next door – the Church in Wales, the Welsh counterpart to the C of E (and yes, it's "in" Wales, but "of" England). The C in W was separated from the C of E, and disestablished and disendowed (i.e. stripped of property) by Act of Parliament, namely the Welsh Church Act of 1914. Disestablishment and disendowment only took effect in 1920 due to the war. This was highly controversial at the time, not least among high churchmen such as yours truly. But I would argue that the Church in Wales is now far better off than its counterpart in England, with attendance actually increasing and with the C in W doing well compared with the stronger Nonconformist churches.
I believe this is because the Church in Wales isn't beholden to Parliament and can reform itself as it pleases. A good example of the C of E's farcically being tied down by Parliament is the attempted liturgical reform in 1928, which failed because Parliament voted it down – and was voted down mainly by non-Anglicans who objected to the content of the reform. Even today, the C of E officially uses the 1662 Book of Common Prayer for the same reason, and the de facto standard liturgy, Common Worship, is officially the "alternative", even though few if any parishes use the 1662 BCP as their main liturgy anymore. This is something straight out of Monty Python, not the New Testament. Surely it would be better for the C of E to no longer be beholden to a Parliament that simply has no expertise in questions of theology, and is substantially made of non-members who aren't affected by the C of E anyway. Today there are atheists and Muslims in Parliament. Nothing wrong with that at all, in fact I welcome it – but really, should they have a say in how the Church of England is run?
Additionally, thanks to disestablishment and disendowment, the Church in Wales is not burdened with the upkeep of ancient buildings, and can rebuild and refocus. To put it in economic terms, the feedback loop between the church's actions and its financial health is thus far smaller and faster, so the church is better equipped to adjust and prepare for changes in economic conditions, and thus manage its resources more wisely. The shorter the information has to travel, the more efficient and constructive the response. This is also critically lacking in the Church of England, and these are all reasons why the C of E is so moribund compared to other Anglican churches around the world. If the C of E is to return to the missionary zeal that spread Anglicanism around the globe and made Anglicanism the third-largest church in the world, then it has to break free of the ballast that is holding it back, and I believe disestablishment is the only answer that will have a lasting positive effect.
I think the time has come to not just allow the British monarch and his or her consort to be Roman Catholic. The time has come for the Church of England to stand on its own collective feet. The short-term pain is well worth the long-term gain.
* - While most sources today speak of "James II", that is technically incorrect. James was the second king named James in England – but was the seventh in Scotland. Hence it is more appropriate to number both successions, since at the time the thrones were not actually united, merely occupied by the same monarch. In theory the current Queen should therefore be "Elizabeth II & I", but since the thrones were more or less united under the Act of Union in 1707, it is unnecessary and was abandoned at the accession of Her Majesty. Now the English or Scottish number of succession is taken, whichever is higher.
** - Another little historical trivia bit: The title "defender of the faith" has been claimed by English monarchs ever since Henry VIII – yes, him again. But the real irony is that he was granted the title by the Pope at the time, Leo X, because of his orthodox Catholicism and anti-Lutheran positions. Henry just kept using it after the split with Rome, and passed it on to his successors.
