Horseriding is easy, a lumpy bicycle with legs. The proof is before us in the sparkle of the seven-year-old girl's smile as she whizzes round the paddock, twisting cutely in the saddle to wave to her daddy outside the ring. Sit up straight, squeeze thighs, feet in stirrups, kick nag in belly, walk, trot, canter. Next stop Cheltenham.

"So you've done this before?" asks Declan McGarry, owner of Irelandonhorseback.com and a former European silver medallist at showjumping.

"Nope."

"And how long have you got here?"

"Two days."

A grin dawns across his face, like January sunlight. "Right."

The first epiphany of learning to ride a horse belongs to the animal: there is an idiot on my back. The second is all yours and arrives the next morning, with the realisation that your eyelids are the only muscle you can manipulate in comfort. You expect your behind to hurt because everyone says it does, and you are prepared for a degree of stiffness in the thighs and perhaps an achy back. These all come in spades, but with the added bonus of foot cramps, chafed calves, neck set in concrete, knackered knees, bruised fingers and, most delicious of all, kidneys that think they've spent a week hung upsidedown being repeatedly clobbered with a lead pipe. "Two days afterwards is the worst," says Declan. Can't wait.

I am cocky about the prospect of saddling up, for such skills are latent in the genes. The Irish, of course, are delivered from the womb into a saddle; as a national vocation it is up there with ballads and bricklaying. Without them there would be no English horseracing, no moon-faced, half-starved jockeys urging snorting thoroughbreds on to finish lines from Catterick to Chepstow; no gimlet-eyed trainers to whom the preparation of horses is closely guarded sorcery.

Being Irish, particularly in England, one is assumed to have mystical insight into the equine arts, to be born with some extra-sensory shortcut to the animal's soul - particularly useful when predicting Gold Cup winners. What does it matter then if personal experience of horses begins and ends with laughing at the kids in the suburbs of Dublin as they careered bareback on piebalds through council estates, roaring obscenities at passing traffic? That, and infrequent contributions to the bookmakers' benevolence fund.

But how difficult can it be? To learn in a weekend, I travel to County Sligo, accompanied by my girlfriend Jenny. We fly on Friday evening to Derry, cross the border at Lifford and drive south through darkened Donegal on a once-notorious road, much improved in recent years by the European Union's deep pockets and Ireland's belated discovery of international trade. We arrive late in Sligo town, tucked into a recess in the Atlantic coast between Donegal and the broad shoreline of Mayo, and check into the Sligo Southern Hotel.

Declan picks us up the next morning and drives the three miles or so to his complex at Carrowmore. It is impressive: a sizeable indoor arena, outdoor all-weather paddock and stabling for up to 50 horses. And its location is beyond compare: this was allegedly the first part of Ireland settled by man and is dotted with megalithic tombs, some 4,000 years old; the great mountains of Ben Bulben, Yeats's muse, and Knocknarea, on whose summit is the alleged tomb of the warrior queen Maebh, dominate the skyline, while Sligo bay shimmers below in the sunlight. Which is strange in itself. North-west Ireland is not accustomed to sunshine in March, or at any time of the year for that matter. "We didn't have a week like this the whole of last July," says Declan, slightly thrown by not having to crack jokes about his horses' love of swimming.

Before we greet the beasts, Declan goes off to find us some half-chaps -knee-length leggings that zip up behind the calves - and a pair of sturdy helmets. "You've got a big head," says one of Declan's more perceptive young pupils who is helping us on with the gear. Irelandonhorseback.com usually takes its pupils for at least a week, pacing beginners gently between lessons at Carrowmore and languorous treks to the summit of Knocknarea, or along the Atlantic shore to the nearby Markree Castle. We, however, are in for a crash course, preferably not in the literal sense.

Jenny is worried because her horse is called Rebel; she would have preferred Lackey, or Pushover. Mine is Dot.con, surely indicative of a dishonest and manipulative temperament. To get the basics, we go to the outdoor paddock and scramble on board without serious embarrassment; we are shown how to hold the reins (three fingers on top, pinkie beneath), how to place our feet in the stirrups (toe on the metal, heel pointing down) and, crucially, how to steer (pull left, pull right, oddly). Walking in a circle is fine and comfortable. "Now we'll try a trot," says Declan. "Kick him on a bit." The horse is initially reluctant, sensing his rider has ambi tions that outweigh his competence. But he complies and the effect is akin to wheeling over speed bumps on a tricycle. Backside bounces up and down in the saddle, feet begin to slip from stirrups and a debutant tumble is narrowly averted. There is a rhythm to be learned when trotting, rising up and down in time to the horse's motion - it escapes me completely. "You'll get it after a while and never have to learn again," Declan assures us, but this seems doubtful. After an hour or so, Declan confesses that he is pushing us a bit harder than is normal on a first outing, "seeing as you're only here for a weekend". Beneath rivers of sweat, we feel tough.

After a brief rest, open country beckons. We saddle up again with our guide, Micheál and saunter off down narrow lanes of dry-stone walls, past the holiday homes of Germans that get all the best views of the bay. Barking dogs emerge from farmhouses but only one succeeds in spooking the horses; Dot.con breaks into a startled canter, straight towards a brick wall and looks set to give an intro ductory lesson in jumping before pulling up. He is cantankerous thereafter and insists on dipping his head at every fresh-looking blade of grass.

We emerge on to the beach where sandbars run between shallows, a herd of seals basking and splashing on the furthest bar. The horses visibly relax and head for the water, wading in up to their bellies and soaking our feet - their favourite part of the job, apparently. Micheál tells gleefully of tourists who failed to follow his lead and had to be fished out of the deeper water.

Towards the end of the ride, as we head back to the stables, the aches set in and toes seize up with cramps. To dismount is blessed relief.

After an unenergetic night in Sligo, next morning is a cornucopia of pain; rigor mortis has all but set in as we arrive back at Carrowmore for more lessons. But lo, trotting around the indoor paddock "it" arrives: my backside stops bouncing and I am moving in time with the horse, up and down, up and down, feeling like John Wayne, only stiffer. "Now you have it," says Declan. "Of course, cantering is totally different."

Way to go

Getting there: Ryanair (0871 2460000, ryanair.com) flies Stansted-Knock from £80 return and Derry from £10 one way.

Courses: An 'Improve your riding' course from Irelandonhorseback.com (Carrowmore, Co Sligo +87 230 4828, irelandonhorseback.com) costs €700 in high season (June 28-August 30) low season €540, single supplement €40, non-riders €300, including seven days' half-board and 18 hours' riding, instruction and trekking.

Upgrade to Sligo Southern Hotel (+71 62101, sligosouthernhotel.ie) €250. Transfer to and from Knock airport €40. The Markree Castle Trail costs €1,625, non-rider €990, single supp €180 inc five nights' half-board at the Sligo Southern hotel and two at Markree castle (markreecastle.ie). The Atlantic Coast Trail costs €900 all year, single supplement €80, upgrade to seven nights at Markree Castle €325. Equestrian Holidays Ireland (ehi.ie) offers riding holidays in 16 locations.

Further information: Tourism Ireland (0800 0397000, ireland.travel.ie).

Country code: 00 353.

Flight time Stansted-Knock: 1hr, 25mins.

£1 = 1.38 euros.