Playing with fire: It's Carnival night in Ottery St Mary, the culmination of the Tar Barrel Sub-Committee's year. Roberta Mock reports

The 50-ft bonfire mound is close to toppling, the visiting fairground is open for business, and the Carnival Queen has been duly crowned. It is one week before Guy Fawkes night and Andy Wade, chairman of the Ottery St Mary Carnival, is reflecting upon the 20,000 spectators who will today swarm into the East Devon town in search of cheap pyrotechnical thrills. 'They come because we're providing a unique spectacle,' he shrugs, 'but we don't really want the people here'.

November the fifth has a special significance for Ottregians. Fire events are held all day, beginning at 5.30am when parties gather around town to explode hand-held gunpowder-filled instruments known as 'rock cannons' and culminating that night with the 'rolling' of flaming tar-barrels through the streets. These 17 barrels are the feature attraction of Carnival Day, ranging in size from the small 'boy's barrels' carried in the afternoon, through to the medium-sized women's and youth barrels, to the 'gert big unz' for the men.

The men's barrels are typically eighteen-gallon sherry-type casks with their ends knocked out. They are coated with pure tar several times during the year by the anonymous Tar Barrel Sub-Committee, stuffed with paper and straw, and secreted at 'various locations around the countryside'. At 8pm on Carnival day, the first of the men's barrels is set alight at the Half Moon pub and allowed to burn until it 'snecks' or 'crackles'. It is then released to a waiting 'roller' who raises the barrel onto his shoulders and charges through the crowd shouting 'uppard' or 'downward', depending on his choice of direction. When the barrel becomes too heavy, or the heat too intense, the roller is relieved of his burden by another man. This process is continued until the barrel has disintegrated. Throughout the evening, new barrels set off sequentially from local pubs, until the largest and heaviest 'hogshead' barrel collapses at midnight in the centre of town.

There are no winners or losers and no rules or goals beyond keeping the barrels aloft and burning as long as possible. 'Barrel rolling is a concept of teamwork,' says Andy Wade. 'We are trying to create camaraderie and are totally committed to perpetuating a tradition.'

Very little is known about the custom's origins, believed to have begun in the 17th century and revived in 1956 after a lapse of 18 years. Some historians have linked it to Shrovetide football, a sort of rugby with minimal rules. Others say it originated with smouldering barrels placed in shops for the purpose of fumigation during plague years. An Exeter University lecturer offers the suggestion that the barrels represent inverted pregnancies.

The 50-odd rollers jealously guard their rights to carry barrels and only those deemed suitable are given the honour by an election committee. Whereas in the past preparation entailed fuelling up in a local hostelry, proper training is not uncommon for modern rollers. But contact with the barrels is limited to the event itself. 'Every year is a practice for those who have not attained perfection,' according to Wade. 'Your peers know when you have become a perfect roller.'

Claire Pollard is a dental nurse who has been rolling barrels, like her father and grandmother before her, since she was ten years old. 'You can't analyse it,' she says. 'It's just something that gets in your blood. When you are running through the crowds, you feel like Moses crossing the Red Sea. They just part to let you through.' Her fiance, who is in the army in Germany, comes home every year for the barrel run. 'He doesn't mind missing Christmas, but he would never miss the Carnival.'

There have been surprisingly few casualties recorded over the centuries of barrel rolling. Although the only specially protective clothing worn by the rollers are gloves made of sacking, injuries seem to be limited to singed hair and bruised upper vertabrae from the weight of the barrels. According to Andy Wade, only the congestion caused by growing numbers of spectators will cause the demise of Ottery's tradition. 'It's a bit like the cliff path syndrome. The more people who are aware of it, the less attractive it becomes.'

He offers a few words of advice to undeterred visitors: don't bring pushchairs, don't wear expensive clothing and don't try to touch the barrels. 'Best of all, don't come.'

Other fire events: The Cliffe Bonfire, Lewes, East Sussex, today; Hatherleigh Fire Festival, Devon, 10 Nov.

(Photograph omitted)