Witches go on-line, off-broomstick

In 1937 a retired civil servant called Gerald Gardner, having recently moved to the New Forest, met a wealthy spinster with the rather wonderful name of Dorothy Clutterbuck. After they had got to know each other, she confessed a secret: she belonged to a nearby coven of witches, which had existed in hiding for nearly 2,000 years. Their rituals were concerned not with the traditional broomsticks and potions, but with the worship of an ancient nature-goddess called Aradia.

Gerald Gardner was soon initiated into this coven himself, earning the right to call himself a Wiccan - old English for witch - and to copy Dorothy's precious Book of Shadows, the coven's liturgy. Membership was dwindling, however, and Gerald was eventually allowed to break his vows of secrecy and publish a fictional account of their Craft, High Magic's Aid, followed by the autobiographical Witchcraft Today.

The effect was remarkable. Post-war Britain was hurtling into the television age: Gardner was an adroit manipulator of his own image. Well-publicised spats with the notorious Aleister Crowley, at one time also a member of the coven, and various other disciples over obscure points of liturgy, and revelations about nudity - "working skyclad" - fuelled media interest. Wicca's emphasis on liberating the individual consciousness left it perfectly positioned for the Sixties; its use of sex rituals kept it booming through the Seventies, and its eco-orientated philosophy made it perfect for the Eighties and Nineties. There are now an estimated three-quarter of a million Wiccans, while a search for Wiccan sites on the internet will give you over 57,000 to choose from. It is claimed to be the fastest-growing religion in the West.

But just how authentic is Wicca? Well, there are strong arguments for the survival of paganism. After all, the early Christians never bothered to physical relics of the old religions, like Stonehenge, so it's reasonable top suppose they were equally relaxed about its practitioners. It was not until the 11th century that Canute thought to actually make it illegal to "worship heathen gods, and the sun and the moon, or forest trees of any sort, or witchcraft." And an amateur anthropologist called Charles Leland found pagan practitioners in rural Italy as late as the 18th century.

Gardner's Book of Shadows, finally published only a few years ago, seems to bear out this historical continuity. It has snatches of a secret language - the so-called Bagahai Rune - whilst the injunction to be "naked in your rites" parallels a Tuscan spell recorded by Leland. There are similarities with elements of the cabbala and the corpus hermeticum, and the preface explains the need for secrecy by warning that witches who were caught risked "going to the pyre".

Unfortunately, it also contains bits of Kipling. The Bagahai Rune is probably an old Basque folksong, and other parts are cribbed from Yeats's Order of the Golden Dawn. Moreover, a witch in Hampshire wouldn't have risked the pyre: in England, witches were hanged, not burned.

Yet, just as Christianity survived the Victorian realisation that the Bible isn't all gospel, so the accusation that Wicca is a made-up religion seems not to have dented its popularity, but rather to have liberated it from the dogmatists and allowed it to evolve into many different forms or "traditions": Saxon Wicca, Feminist Wicca, even Native American and Aboriginal Wicca.

When I began researching a novel about witchcraft, set mainly around the Scottish witch trials of the 17th century, my heroine, a feminist academic, is looking for proof that a so-called witch's real crime was not devil-worship but lesbianism. I found that a tiny sub-plot about modern-day Wiccans gradually took on a life of its own, and a new theme emerged: humanity's extraordinary need to reinvent its past. For every writer, Wicca's success is a reminder that what is written as fiction doesn't necessarily stay that way.