How do you crown a king in this day and age? Slap a paper hat on his head and tell him to get a proper job, some might say; but there will not be a republic any day soon.
The debate about the monarchy will spring back to life when Her Majesty the Queen dies, as sadly we all must, but the next coronation will still be a huge state occasion, a moment that redefines the nation. That is why, for the first time, people of other faiths will be invited to take part.
That's a fact, in my understanding, although the Church of England will not yet admit it. The Archbishop of Canterbury and other church leaders who will devise and put on the service refuse to talk about a future coronation publicly, saying that to do so while the Queen is still alive would be "very improper". But privately, in conversations over the past 18 months, they have told me they accept the need to be "hospitable" to other faiths.
So Muslims, Hindus, Jews and others can expect an invitation to play some part in this grand occasion, which has been explicitly and exclusively Christian for a thousand years.
This dramatic shift will dismay traditionalists, as did Lord Harries on Friday. The former Bishop of Oxford has been making headlines with the suggestion that passages from the Koran should be read in Westminster Abbey when the congregation is seated, before the ancient Christian service starts. But Douglas Murray, who writes for The Spectator, said: "If the coronation of the next king and the person nominally Defender of the Faith of Christianity in this country opened with readings from the Koran, I can assure there would be a great amount of people taking a great amount of offence."
But the Harries plan is a red herring, as I understand it. Muslims and representatives of other faiths are unlikely to be asked to read from their sacred books before, during or after the service. Instead, they may be asked to light a candle, plant a seed or take part in some other symbolic act, or read a passage that is not regarded as scripture but which reflects common values.
This would happen during a pause in the coronation liturgy, some of which is enshrined in law. The Coronation Oath was defined by an Act of Parliament in 1688, for example. However, the words, music and rituals around that central liturgy can be designed to reflect who the Church and the Crown think we are and what we believe in – even if that is more based on hope than reality.
Atheists should not expect an invitation. They may be on the rise in Britain, and may be playing an important part in the debate about our national values, but the coronation is built on the belief in a higher power.
"This is an ordination," said one very senior church leader, citing what happened in 1953. "That means setting someone apart for a particular calling and purpose. At the beginning of the service, the Queen comes into the Abbey, goes to the altar and kneels in silent prayer. She is making her allegiance to God before anyone makes allegiance to her."
The Archbishop of Canterbury will write the service, as holders of that office have done since 1066. The Most Rev Justin Welby will have help from senior advisers, as well as the Dean of Westminster, Dr John Hall, who will host the service.
Westminster Abbey already welcomes the Queen to an annual Commonwealth service including representatives, words, symbols and even prayers from other faiths. However, the stakes are higher at a coronation. This is a truly once in a lifetime event with an audience of billions, and the leaders of a church that is already bitterly divided in parts will not risk giving its many watching critics any chance to describe it as a "multi-faith service" that treats all gods as equals, upsets some people and satisfies none.
Can an exclusive Anglican coronation service with elements that go back to the Reformation and beyond really reflect the reality of life in modern Britain?
"There is always a way to reflect it," said the very senior source. "But you have to reflect it very carefully. Otherwise you just get into daft syncretism." That is the combining of contradictory beliefs to make something nobody believes in. "The key thing about liturgy is that it starts where you are. Wherever we are, it will be very different from 1953. Consequently, the coronation has to start with where the nation is and work with that."
The last one was a Technicolor blaze of certainty designed to cheer Her Majesty's subjects at a time of postwar austerity, when the empire was shrinking. At its heart was an old deal being made new: the Church of England declaring that young Elizabeth had been chosen by God to rule; and she in turn promising to uphold its faith alone. Legally, those vows must be made again next time in much the same form, but reality is at odds with their view that this is one nation under one God.
The British have changed dramatically since the Fifties. Thirty three million people still call themselves Christian, but only five million belong to a church. The rest have lost faith in religious institutions, if not in faith itself. There is a new, loose, individualistic but nevertheless vibrant national folk faith alive in this country, informed by Buddhism, neopaganism and pop culture as well as the incoming religions of the world, but also "haunted" – as the former Archbishop of Canterbury Dr Rowan Williams put it – by Christianity.
You can hear it in the crematorium when his namesake Robbie sings "Angels", or see it in roadside floral tributes, where someone will always have written: "You are the brightest star in the sky."
Then there are 2.7 million Muslims, 817,000 Hindus and 263,000 Jews, as well as many people of other faiths. There are also 3.3 million so-called "hard atheists" who have no faith and see religion as a negative force in society. Let's not even talk about the Jedis.
Even other Christians are usually excluded from playing a leading part in the Coronation. The Moderator of the Church of Scotland was permitted to present a Bible last time, a concession seen by some Scots as patronising.
"The real problem here is the Church of England," says the Rev Dr Doug Gay, Principal of Trinity College at Glasgow University. He accuses Buckingham Palace and Lambeth Palace of "sleepwalking" towards a coronation that would alienate more Scots – not to mention others – from the monarchy and the British state.
"The last coronation was an ecumenical disaster, with the Archbishop of Canterbury refusing to serve communion to the Moderator of the Kirk and other non-Anglicans. The senior minister in Scotland's largest Christian denomination was treated like some kind of minor rural dean. The danger is that they have learnt little in the past 60 years."
Others will fear the same, but my understanding is that the Archbishop and others are not "sleepwalking" at all. Rather they are discreetly considering how to make this more of a shared moment, even while hoping it is a long way off.
So here's a suggestion, based on what is working for churches right across the country, not to mention a certain arch-populist, right-wing politician who drapes himself in episcopal purple. If we really want a Britain that lives up to Christian ideals of fairness and equality, why not hold the whole thing in the pub?
Cole Moreton is the author of 'Is God Still an Englishman? How Britain Lost Its Faith (But Found New Soul)' (Abacus)