Until quite recently the Church of England was sometimes called “the Tory party at prayer”. Today this could hardly be further from the truth: the Church looks more like the Lib Dems at prayer. As for the Tory party, it now chooses to pray elsewhere.

For more than a decade, the most prominent religious voices in the party have been Roman Catholic rather than Anglican. When John Gummer and Ann Widdecombe converted to Rome in 1993, after the Church of England’s decision to ordain women, they were representing a wider trend. When the Duchess of Kent joined them there was a flurry of media interest — could England be on the verge of reconversion? The question was not entirely fantastic: Catholicism became an increasing presence in the British Establishment in general, and in the Tory party in particular. Within a decade the Tory party was headed by two Roman Catholics, Iain Duncan Smith and Michael Ancram. The Tory press has seen a similar transformation. The editorship of The Daily Telegraph recently passed from one Roman Catholic to another, under the ownership of another.

A generation ago, the Tories’ Roman tendency would have scarcely been credible. Tories were Anglicans, almost to a man: Churchill, Eden, Macmillan, Hogg, Powell, Heath. To understand this shift in the Tories’ religious allegiance we must consider the party’s disenchantment with the Church of England as well as its attraction to Rome.

The Tories were the party of the monarchy and the established Church: they sought to protect these institutions from the reforming zeal of the Whigs, to defend the common national faith. This remained the case well into the 20th century — until the 1950s, in fact. Then came the 1960s: dramatic secularisation effectively ended the Church’s traditional role of the nation’s moral guardian. In effect, the Church was semi-disestablished by 1980. As its identity became less national, it became more radical. It moved away from its Tory image, and it often pursued a global agenda (poverty, disarmament), at the expense of what the Right called the national interest.

With Thatcher in power, it was clear that the Church of England was no ally in the new national crusade against socialism. The Tory party and the Church sometimes seemed to be rival representatives of the national soul. When a Tory spoke up for “traditional values”, a bishop would quickly sneer at the presumption. And when the Church outlined its social concerns, as in the Faith in the City report of 1985, the Government cast doubt on the Church’s motives. It soon became a basic tenet of Thatcherism that the established Church was untrustworthy: it committed the dual sin of neglecting the national interest and neglecting the true business of religion.

By this time Roman Catholicism had lost its traditional aura of a foreign ideology. Cardinal Basil Hume, Archbishop of Westminster from 1976 until his death in 1999, was thoroughly English as well as palpably holy — he was part of the Establishment to a far greater extent than any predecessor since the Reformation. He was the culmination of a process that began in the early 20th century: the revival of an English form of Roman Catholicism. For more than three centuries the old faith had been seen as deeply unpatriotic, as the continental enemy tended to be Catholic. In the 20th century this was no longer the case, so an English Catholic revival became possible. G. K. Chesterton energetically sought to reconcile John Bull with the Holy Father, and figures such as Knox and Waugh carried on this work in their different ways. When cultural Anglicanism began to weaken, Roman Catholicism began to emerge as a substantial part of what remained of the national religious scene.

For those Tories who converted to Rome in the 1990s, the issue of women priests was symptomatic of a much wider liberal agenda in the Church of England. Rome, by contrast, seemed reassuringly traditional. It also seemed mercifully free of a political agenda. When the ageing Alan Clark flirted with faith in the late 1990s, it was not with his native Anglicanism. He blamed the Church of England for promoting political correctness at the expense of national pride. His Last Diaries reveal that his vague spiritual yearnings had become focused on Rome.

The Tories’ resentment at liberal Anglicanism is still going strong. There was a good example in The Sunday Telegraph a few months ago: a leading article called Rowan Williams “An Unworthy Archbishop”, for daring to criticise the treatment of suspected terrorists. Tory orthodoxy still entails the claim that the Church of England is a failed guardian of the national soul, which is safer in Tory hands. And, for many Tories, in Roman Catholic hands.

But what about Rome’s old image as essentially unpatriotic? During the second half of the 1990s this evaporated with startling speed. The Queen herself began to demonstrate her openness to the old religion: she attended a service at Westminster Cathedral in 1995, and later invited Cardinal Murphy-O’Connor to officiate at Windsor. It became commonplace for her to treat Roman Catholicism and Anglicanism with equal respect — this was especially evident in her Christmas broadcast of 2000, in which she paid homage to the Pope.

The Prince of Wales has let it be known that he finds the Act of Settlement, barring Catholics from the throne, an embarrassment. Perhaps he has fantasised about doing an inverted Henry VIII, and breaking with Canterbury for Rome.

Theo Hobson is the author of Against Establishment: An Anglican Polemic (Darton, Longman & Todd, £7.95; offer £6.76)