In reality, it was no "extraordinary" act of public penitence at all, but the familiar words of the general confession from the Communion service of the Book of Common Prayer. Stirring stuff, certainly, but a prayer that once every schoolboy knew.

Something has gone wrong. Those words penned by Thomas Cranmer more than 400 years ago have grown unfamiliar. Worse, they have been replaced by "tired and trite" language designed to be accessible to modern worshippers. That is the complaint of Canon Glyn Webster in a preface to the new edition of The Church of England Year Book.

He ought to know, because he is Chancellor of York Minster and a bigwig in the General Synod. "We are in danger of losing so much," he says, referring to the beauties of the Prayer Book and the banalities of its replacements. "Perhaps we have lost it already."

We have, Canon. And the first people to notice we have lost it are, oddly enough, those who seldom go to church. Ordinary folk who crowd in to Midnight Mass for Christmas (having found something more pressing to do all the sabbaths of the preceding year) immediately discover that they cannot join in. They don't recognise the prayers. Even the Lord's Prayer has been meddled with. They can't find their place in the service book, or among the sheaves of printouts from the internet that now supplant it.

Instead of declaring that the burden of his sins is intolerable, the casual visitor is expected to ask God's pardon for things he has done "through ignorance, through weakness" because "we have wounded your love, and marred your image in us". True enough, but neither familiar nor so urgently clear as the old Prayer Book.

The Prayer Book is an institution, and it embodies the spirit of the Church of England. To destroy an institution is to scatter to the winds the values it should pass down to the next generation. There is a parallel in the destructive attacks on the monarchy, the House of Lords, Parliament itself. Knocking down is easy. To build up again almost impossible.

The Prayer Book is like a wonderful cathedral such as York Minster, or the historic church in many a parish throughout the land. The medieval village church is not there to be demolished in favour of a staring electric-lit, carpeted prayer hall with coffee facilities and lavatories. It belongs to no small committee.

Happy-clappy Christians will counter that services using the 1662 Prayer Book are nearly empty, while the crowded, enthusiastic gatherings are those that use the new, pick-and-mix, internet-download Common Worship - or, better, a "liturgy" devised for the congregation. They like meeting in comfy, carpeted surroundings too.

Why not?

That attitude sounds bright and welcoming, yet under the surface it is cliquish and defeatist. Deep down it strikes at the essence of Christianity.

Christianity is a gift from its founder. It was not devised by a group of well-meaning human beings as a programme of appealing, popular ploys. In private prayer, where, on the advice of Jesus, you go into your room and shut the door, you speak in your own words, one-to-one with your Father. In public worship, it is quite otherwise.

Public worship is the inheritance of the Church, which is the Body of Christ. No one with a conscience dare disregard the command of Jesus: "Do this in memory of me." So, for the service of Holy Communion, or the sacrament of Baptism, for example, it is impossibly wrong to try a DIY approach.

Not even Archbishop Cranmer started from scratch. Phrase by phrase, his Collects followed ancient prayers from the old Latin Missal. Sometimes he used prayers evolved in the Eastern Church. He even took in material used in Spain under Islamic rule - Cranmer's copy of Cardinal Ximenes's edition of the Mozarabic rite, printed in 1500, is, I think, still in Lambeth Palace Library, though I haven't seen it.

We need not quite buy Canon Webster's argument that "English was flourishing" when Cranmer was writing, while today all we have is Estuary English. Try reading most books written in the mid-16th century and you'll find them almost incomprehensible - crabbed, irregular and turgid. Shakespeare, a bit later, was the exception.

The greatest blessing for the language of worship is to be left alone. Strange phrases become familiar and beloved; the least obvious grows transparent through use. "Prevent us, O Lord, in all our doings," might be misunderstood by a child. Once the meaning is learnt, the archaism is no obstacle. Archaism goes towards dignity, gravity and beauty. They realised that 400 years ago, and elevated their speech in formal prayers, never thinking the newest street slang would improve it.

To the common inheritance of the body of Christendom, held in trust, there is a public right of access. Irregular churchgoers least of all should be offered the latest fad of the local "liturgy" committee. True democracy includes the votes of generations who went before and decided to leave a heritage not for squandering. That argument is a conservative one. But this is a conservative newspaper.

The burial of the Book of Common Prayer is a scandal, literally a trahison des clercs. The clerics have betrayed the unlettered; the shepherds have driven the sheep on to dry pastures. Canon Webster is right to remark that "what seemed fresh and modern in the 1970s can seem tired and rather trite today", but it was the Synod, in which he plays a leading role, that mashed up the tired and trite hotchpotch now on the menu.

As Canon Webster's predecessor at York, Dr Edward Norman, pointed out in his brilliant book Secularisation, attempts to tailor church worship to people's ordinary expectations - entertainment, emotional self-fulfilment, choice - end up turning them away from the demands of God-centred religion. "What they are seeking," he concludes starkly, "is not Christianity."

END