The Church of England has announced its plans to celebrate the Diamond Jubilee  later this year. It is hoping that all its 13,000 parishes will involve themselves with initiatives including The Big Jubilee Lunch, which "will see millions across the country joining together to have lunch on the afternoon of Sunday, June 3rd", and The Big Thank-You , in which churches and cathedrals will invite members of the congregation to add their names to a collective thank-you letter to the monarch. Containing an introductory paragraph by diocesan bishops, the letters "give the public a chance to say a few words in appreciation of 60 years of loyal service."
In some ways, this is the Church of England doing its job. The Establishment "deal", as conceived centuries ago, gave the Anglican church immense privileges within society (bishops in the House of Lords, for example) in exchange for the church giving its moral backing to the state. The monarchy remains the most visible symbol of the church-state link. As Supreme Governor of the Church of England, the Queen receives the "homage" of bishops on their appointment and even ordinary parish priests are expected to swear an oath of allegiance to her. Prayers for members of the royal family are offered daily in every C of E church in the land. (Francis Galton, the Victorian scientist and inventor of eugenics, once did a statistical analysis of the life-expectancy of members of the royal family and concluded that the prayers didn't work.)
The Queen promised in her Coronation Oath to "maintain and preserve inviolably the settlement of the Church of England, and the doctrine, worship, discipline, and government thereof, as by law established in England" and to "preserve the rights and privileges" of Anglican clergy. But her formal religious duties are in fact fairly limited. She distributes symbolic coins to worthy pensioners at a cathedral each Maundy Thursday, and offers a prayer at each State Opening of Parliament that "the blessings of Almighty God may rest upon your counsels." Her presence at the annual Remembrance ceremony at the Cenotaph might also be regarded as a religious occasion. At least technically, certain church appointments (such as parishes within the Duchy of Lancaster) are in the direct gift of the Crown. By and large, though, the monarch's position as head of the Church of England is a purely symbolic and ceremonial one.
But there's no doubt that the present Queen has taken a close personal interest in the religious aspect of her job. She is, by most accounts, personally devout. Certainly, her Christmas messages in recent years have been increasingly explicit in their Christian content. In the most recent , for example, she pronounced that "God sent into the world a unique person ... a Saviour, with the power to forgive" and offered a prayer that "We might all find room in our lives for the message of the angels and for the love of God through Christ our Lord." The Archbishop of Canterbury's own New Year Message contained rather fewer mentions of God.
So the Church of England's leaders have reason to be sincere in offering a "Big Thank You" to the Queen, not least for living and reigning for so long. Things might not be quite so straightforward under the next Sovereign. Prince Charles's interest in religion is well-known, but it would seem very different from the uncomplicated and quiet Anglicanism of his mother. He has famously expressed a desire to be "defender of faith" rather than "Defender of the Faith", a distinction that may seem more appropriate in a multi-faith society but which also implies a more problematic desire to involve himself in theological debates (as well as leaving atheists and agnostics seemingly undefended). Some of the more traditionally-minded clergy objected to his divorce and remarriage in a civil ceremony. A few even questioned its legality.
The next coronation, if indeed there is a next coronation, is unlikely to be an Anglican monopoly like that in 1953. Will the new king be expected, or willing, to swear to uphold "the Protestant reformed religion established by law"? It seems unlikely. But it seems even more unlikely that the Church of England would give up its official status easily, or even that it will be seriously questioned. I suspect that the C of E will be offering prayers, and even Big Thank-Yous, to monarchs for as long as the monarchy persists. Anachronisms survive best if they stick together.