IN THE decades after the Second World War, the Church of England threw its energies into revising canon law, for the first time since the reign of King James I.

The then Archbishop of Canterbury, Geoffrey Fisher (who was seen by many as an authoritarian law-enforcer, and nicknamed "The Headmaster", after one of his earlier posts as head of Repton School), enjoyed the process as "the most absorbing and all-embracing topic" of his whole archiepiscopate. He seemed to view the canons as school rules that laid down a strict dress code for ministers (Canon B8). Robes were obligatory for holy communion, morning and evening prayer, and the occasional Offices.

These rules seemed sensible in 1964. They reflected the world-view of the post-war Establishment, in the age of sputnik, when Britainhad the death penalty, and Win-ston Churchill was still in the Commons.

Half a century later, the world has changed, but the C of E dress code remains fixed in stone. I would argue that Canon B8 is no longer fit for purpose. It does not reflect the realities of Anglican mission in Britain today. Canons that are dead letters bring the whole of canon law into disrepute, and need revising or rescinding.

The General Synod is about to debate the question of robes in Christopher Hobbs's Private Member's Motion (News, 3 January). It has done so three times before, in 1988, 1993, and 2002. The proposal is very modest - not by any means to abolish robes, but simply to make them discretionary, not mandatory. Twelve years ago, the idea won majority backing in the House of Laity, although the clergy threw it out. Consensus has since been building that the time is ripe for change.

WHETHER robed or not, both styles can be a lively and authentic expression of contemporary Anglican worship. Many congregations where robes are worn are mission-minded and growing churches, seeking to present the gospel in an accessible, attractive, and relevant way to their communities. In diverse contexts, from rural to urban, affluent or poor, cathedral or chapel, robes can be a valuable aid to mission. In some places, to abandon them would foolishly damage the outreach of the local church.

But simply that robes are appropriate in many, perhaps most,C of E churches is no good reason for insisting on them everywhere and always. What promotes mission in one community might hinder it in another.

Robes are glorious in some settings, and can help focus attention on the majesty of God. But elsewhere they are incongruous and distracting. While some outside the Church are attracted by clerical robes, to others, the traditional dress code appears arcane, bizarre, irrelevant, and even derisory.

When it comes to evangelism, one size does not fit all. The people equipped to make the wisest choices about local mission are not the central authorities in London, but those who live and minister in their communities.

Few people, even the most idealistic, would seriously suggest a return to the days when most C of E churches worshipped in a similar way. Common Worship is founded on a different philosophy from that of the Book of Common Prayer, which was enforced by Acts of Uniformity and imposed the same language and style on every congregation. Parishes now have the freedom to choose the form of worship which suits their context rather than have it decided for them. So why is this liberty still refused when it comes to ministerial dress?

CONFORMITY in worship is a dangerous principle. Often, it amounts to majority rule, where 60 per cent of the Church of England says to the other 40 per cent: "We don't want it in our parishes; so you can't have it in yours."

Common Worship wisely encourages us to seek not "unity in conformity", but "unity in diversity". For the sake of consistency, let us extend the same principle to clothing.

The most practical and sensible approach would be to allow the clergy, in consultation with their congregations, to come to their own conclusions about how to dress, based on their local culture and context. Where this has already been tried, for example in the diocese of Gloucester since 2006 (with the permission of the Bishop, the Rt Revd Michael Perham), it has not led to liturgical chaos, nor to "shell-suits in the sanctuary" (as some of the recent press coverage put it).

The clergy are not naughty schoolchildren in need of the headmasterly instruction of Archbishop Fisher. Even as Canon B8 now stands (with no mention of cassocks), a priest could fulfil the jot and tittle of the law by putting a surplice over a T-shirt and shorts at the Sunday eucharist. But no one does, because priests are intelligent human beings who can be trusted to use their common sense.

The strict obligation to robe belongs to a bygone age. If our overriding concern is to become "all things to all people so that by all possible means we might save some" (1 Corinthians 9.22), surely this includes permission to dress in different ways.

It is time for the Church of England to welcome this healthy diversity, and to honour both the robe-wearer and the non-robe-wearer. Our legislation needs to catch up with the realities of worship and mission in Britain today. It is 2014, not 1964.

The Revd Dr Andrew Atherstone is tutor in history and doctrine at Wycliffe Hall, Oxford, and the author of Clergy Robes and Mission Priorities (Grove Books, 2008).