THIS IS a curious place to be on a bank holiday. I am sitting half-way up a precipitous grassy slope, one arm hooked in a bush, buttocks clenching a meagre tuft of grass in an attempt not to slide inexorably downwards, all the while watching six men wave spotless hankies at one another. They appear to be the Persil-washes-whiter-than-white Morris Men, and half of them look like Seamus Heaney. (The rest resemble Sir Harrison Birtwistle.)

Although some brandish sticks, others garlands, hoops or staves, some wear pumps and others DMs, basically there are three types of Morris dancer. I can say this with some confidence having watched teams from all over the country clog it all afternoon. There are the wholesome Morris Maidens, in broderie anglaise knickerbockers and colourful pinnies, with scarlet cheeks and flowers in their hair; there are the real-ale, village-green traditionalists, or Heaney-Birtwistles; and finally there are the Morris Satanists, the missing link between the English Folk Dancing Society and occultist Aleister Crowley. They wear pentacles and horns, blacken their faces or don masks, dress in Gothic tatters and stamp to the pagan drum rather than the jolly accordion. One of their number is even sporting remarkably convincing hairy hindquarters and cloven hooves. But everyone, absolutely everyone on this sunny bank holiday in Hastings, is swilling pints of beer.

We arrive in town just as the grand Jack-in-the-Green procession commences, down by the sea. "Jack" is a huge masked figure, crowned with flowers and stuffed with leaves, who jumps and wiggles at the head of the parade, attended by green-faced bacchants festooned with ivy. A mad sponger is dabbing lucky green on the faces of participants and passers-by. The Morris dancers follow in convoy, some essaying complex steps, most marching or simply trailing drunkenly along. It seems antithetical to the anarchic spirit of the May to be in any way disciplined. One group attempts to get in formation, its portly members holding up the entire parade as they stumble into step. Just as they are poised, hankies aloft, the next troupe rushes forward and successfully interpenetrates for a few confused moments. Regrettably, there is is some kicking and pushing in the ranks of the Morris men before precedence is re-asserted.

The parade seems to go on forever, and just when you think there are no more revellers you look down the lane and glimpse more furled hankies, or flower-sprigged top-hats, or antlers in the distance. Finally, the last stragglers caper past, and we make our way up to the top of the cliffs in their wake.

Hastings castle, jagged as a broken tooth, is sliding slowly into the sea, and since hundreds of pagan sun-welcomers are packed inside its bailey, there's a possibility that we'll slide with it. "Hundreds of Morris Dancers Killed" runs the imaginary headline for what will no doubt become known as the Great May Day Disaster of 1996. All the official deckchairs have been grabbed, so we clamber up to a patch of grass on a 45-degree slope and hang on - hence all that buttock-clenching. The show is worth a bit of discomfort. The sun is shining, the dancers foot it on a hastily rigged stage on the grass, the castle walls form a natural wind-break and amphitheatre, and beyond the sudden drop the sea rises up and takes possession of seemingly half the sky.

Individual dances are called things like "Not the Bloody Stick Dance Again" or "Jaffa-Cake stomp", and one of the most startling is named after Captain Webb, of cross-channel swimming and box-of-matches fame. A female troupe from Leicester sing shrilly "swimming along, swimming along" while pretending to be waves, with a statuesque lady in a purple leotard and snorkel cavorting between. This gets huge applause, as does the Maddy Prior soundalike who sings an interminable self-penned dirge: "follow the drum ... celebrate the great May Day ... come and sing to release the summer". My favourites are a malevolent bunch of low, mean, inner-city muthas, who look like they're fuelled by snakebite and bile. They are completely covered in masks and black rags, and their musicians set up a furious clamour as the dancers howl and spin. Our friend is getting all misty-eyed about his own Morris days with the Deptford Mud Rats or some such, and highly approves of the baby-frightener school of dancing. "It should be scary," he says.

Then, behind and above us an insistent drumbeat begins. Jack in the Green has been installed at the top of the castle, his attendants are beating hell out of anything they can find, and the climax of the celebrations is approaching. In vain the last dancers foot it gaily: everyone is fighting their way up the slope to watch. The drumbeat intensifies, three drunken lads climb up the walls and wobble hilariously, Jack quivers and shivers, aware that his hour is nearly come. I wonder what Sir James Frazer would make of it all? Jack yomps down the hill, shedding foliage, and makes it to the stage, where he is raised in the air and dramatically lowered. Suddenly he disappears under the weight of pagans, and leaves and branches fly through the air, grabbed at wildly by the crowd. Jack has been shredded, summer has been drummed in, and the flower people toddle beatifically off to join the queues for the Portaloo.