OK, girls, hands up if you think ball games are sexy. No, really, don't just say so to be nice. There are lots of other sports that are sexy. Mountain climbing, for instance. Or hang-gliding. And steeplechasing is pretty high on the list. But adults running around in pursuit of a ball?

One thing makes a sport sexy: danger. Not faux-danger like bungee jumping, where the only real risk is staining your trousers, but something that requires total concentration because there's a good chance that you'll be dead or maimed without it. Soccer? Dullsville, darling. Tennis carries more risks from nutters in the crowd than the opponent on court. Rugby is getting there; though the intimacy of the scrum is probably as appealing to the lads as the risk of being unable to walk off the pitch.

But there is one sexy ballgame, I found it accidentally the other day. Polo.

Now I know polo has a bit of an image problem. Most people think of it as a game played by people who wear blazers and silk dresses; Drippy Di and her friends leaning on Range Rovers and talking about bums. Say "polo" to most people, they will probably say "Chaz", "massage parlour" or maybe "Julia Roberts". But that's actually an activity called "watching polo". What happens on the field is a different story.

Think about thundering about on half-a-ton of semi-sentient muscle while seven other crazies try to stop you with five- foot mallets. This is the sport of some of the world's fiercest people: the Afghans play it when they're not lurking in mountains. The main square at Isfahan gets cleared of righteous rioters from time to time for a good session of ball-smashing. It's huge in South America.

My rather mild-mannered mate James won half-a-dozen lessons in a raffle the other day. He was after the car, of course, but what the heck. He came back after the first go, covered in sweat and grinning like someone who's just been in a ruck with the Inter-city Firm. "It's the dog's bollocks," he said. His eye had a steely glint. Better give this a go, I thought.

The nearest place to London that you can learn is at Ascot Park, near Sunningdale. It belongs to Peter Grace and his four daughters: one of the most beautiful families that ever waved a block of wood in someone's face. The girls - all hair and flawless skin and legs - have their own team and thrash the daylights out of anyone brave enough to take them on. They give two-hour starter lessons on a Sunday morning for pounds 70. This may sound steep, but a polo pony can cost anything up to 40 grand, and they lend you theirs.

Ascot Park is a spread of flat fields and huge trees that makes you think of Betjeman. Until you look beneath the trees and see the milk crates. I was still reeling from having got up at eight o'clock on a weekend. I turned to the man next to me. He was wearing jeans and a nice woolly jumper. "Do you do this all the time?" He giggled. "Oh no, pet. I went on a donkey on the beach once." "What on earth are you doing here, then?" "Well," he grimaced, "it seemed like a good idea..."

And so to the milk crates. The first hour was spent standing on them, a bit like John Major canvassing, only less dull. The beautiful daughters walked up and down explaining how to hold this stick at its farthest extremity and whirl it through 360 degrees without breaking your wrist. Eye-hand co-ordination was never my strong suit: something to do with an in-built resistance to school sports, probably. But, hell, I'm a devilish horsewoman and I've got the scars to prove it.

Except that a polo pony is a bit different from your average eventer. They work backwards. They have two basic paces - stop and go - and their mouths are different. A normal horse, on contact with the bit, breaks out of its slumber and prepares to move. A polo pony, which you steer with four reins in one hand, understands mouth contact as meaning "go backwards, please, as fast as possible". It took ten minutes just to keep going in one direction for more than five seconds.

Deep humiliation: everyone else was cantering up and down and whooping like mujahedin. I found a ball, slashed at it and apologised to my pony, who winced visibly. "Don't worry. You're getting it!" cried one of the beauties as she peeled off, hair streaming in the wind, in pursuit of an Iranian economist who looked like he'd been born to it. I hate this, I thought. I hate ball games.

And then suddenly it happened. We were cantering. My stick was in the right place - the head wobbling above my own - and we were bearing down on an innocent ball between two divots. Raise arm. Straighten up. Whack! It works! The ball screams away, begging for mercy. But I'm after it now. I'm gonna git you, sucker. Here it comes again. Arm back. Windmill whirl. Hit ground. Lose control of stick. Pony slams brakes on. End of game.

But it's there, I'm hooked. My body is buzzing with adrenalin and I want more. Is this the point? Have I been missing out for the past 20 years?

Later, James plays a chukka and I seethe with envy. Half-a-dozen wiry men have joined in and the pace is frantic. The fields echo with the crack of wood and the clash of stirrups. They race to goal, miss, race back. The ponies' eyes roll and miraculously everyone survives.

At a party later I run into my friend Pete, who shaves his head and teaches stockbrokers to be macho at a Gun Club. "I'm in agony, darling," I say. "I just had my first polo lesson." "Oh, yeah?" he says. "Where did you do that, then?" "At Ascot Park. It's near Sunningdale." "Oh," he says, "I go there. It's the dog's bollocks, isn't it?"