It's a swanky place, the brilliant greens of the golf course, with their frondy fringes of palm trees, surrounding vast deserts of maneges overlooked by a clubhouse drenched in bougainvillea. The horses' shower area has the best view in all the Canaries, over the boil-holes of ancient volcanos down to the sail-studded sea, or up to the cloudy central peaks. The horses themselves live in corridors of small dark boxes, and flap their mouths.

The one we have come to see is an immense Hanoverian so shiny you can see your face in his sides, with blinding white bandages. His owner, a tiny garrulous Finn, reaches up to stroke his shoulder. "He’s such a kind horse”, she says yet again, scuttling backwards as he tums to look at her mildly. I foresee problems of patience already: she repeats everything six times in both English and Spanish, an indication of her idea of norms of comprehension.

I throw her aboard. Her little legs reach just below the saddle flaps as she takes a firm grip on the reins. He wears a snaffle so high his mouth is stretched halfway to his ears, a drop noseband embedded in his muzzle, and draw reins. We shuffle down to the nearest acre of arena, where she hits him briskly. He lumbers off in a heavy trot with his nose stuck out. Lena is of the northern persuasion that you begin work by collecting the horse like a trawler winching in its catch, keeping the revs up with a steady drumming of heels. The horse bears with this for a while, then sets his neck and jaw and tanks across the arena in a series of graceful dolphin-like bounds. Lena yelps and yanks his head between his knees with the draw reins just in time to stop him leaping the white rails, recovers the trot and resumes trawling and drumming. Episodes of trot alternate with bids for freedom until I call a halt.

"He's such a kind horse," gasps Lena, wiping the sweat from her eyes, "but I have to work so hard to get him into an outline, and you see he's naughty."

I dig the noseband out of its groove and remove it, slacken everything, take off the draw reins and climb on, wishing I liked these stolid hunks better. As usual, I ask him nothing. From some profound Teutonic meditation of the sand his mind rises slowly as cream over milk, and finally directs his feet forward. He finds it curiously pleasant, this novelty of strolling around with the reins lying on his neck. He tries cautiously wiggling his neck, then lowers it to the ground and groans.

"Naughty, he's trying to break the reins," shrieks Lena as we glide past. He's so stiff, this poor stone troll, he thinks it's stretching. He does his best at bending, too but he’s as flexible as granite. I take off Lena's air-filled saddle, gel pad and fluff and try palpating and massaging granite. It doesn't actually hurt him: it's just solid. I ride him bareback. No muscle spasms beneath my seat, just rigidity.

"He's not naughty,” I tell Lena, "he just needs to stretch and warm up. Sometimes they buck from fear, sometimes from pain, but he's not frightened or hurting. He wants to buck to stretch." Unfortunately, the inclusion of possibilities already discounted proves too much for Lena, provoking a torrent of protest about the price paid for her saddle and the tenderness with which she treats him, so that the import of the message is lost. I repeat it slowly, six times in both English and Spanish, and continue walking about, bending and stretching him until he comes like well-kneaded bread dough, warm and springy. Suddenly he opts to go faster, floating round the arena in a slow-mo trampoline trot and a thistledown canter. Lena is delighted. "You see, when you've worked him into an outline, he can do it. But you're not controlling him, your reins are loose, that's why he's not naughty."

“Lena, he's NOT NAUGHTY, he just needed to stretch, and you don’t let him. And look, I am controlling him if you want to call it that.” We do shoulder-in, half-pass, pirouettes, flying changes; then Lena gets on and he's a stone troll again, refusing to move from the gate. I persuade her to sit up and let go of the reins, and he's fine, though she hangs on to the saddle at a trot. I veto drenching him in ice-cold water immediately, and turn him loose in the lunging circle, where he rolls and rolls and shakes and rolls. While he meditates on the sea I talk to Lena about blood circulation and shutting big wet trolls in coffins.

"Tomorrow morning, don't tack him up and we'll look at another way of

warming him up that'll suit you both better."

"Oh I know how to lunge him but I lost the side reins and then he's so naughty."

"No, I mean letting him do it himself. He needs to stretch, and he knows which muscles need stretching better than we do,"

We cover him in bandages and protectors and turn him loose. He meditates until the cream rises and his feet move him into a realisation of liberty. Dazzling explosion of choices! To roll first, or leap? Run or paw, or scratch, or frolic? How many different types of buck? When he has exhausted his rather limited imagination I get in and shoo him about until he lowers his head and the trampoline comes back and he's ready.

"Now ride him, Lena. Don't worry, I'll clean him while you get the saddle. You won't need the draw reins."

He was, she said, marvellous, after we had worked at loosening her too. She even enjoyed cantering. Her fear of him had somehow escaped my calculations until she confessed how she dreaded the moment when her teacher asked for a canter.

"He's so strong when he's naughty. But he wasn’t naughty at all today, he's having a good day."

I felt sorry for the poor troll, so I really tried with Lena. Her teacher had filled her with all sorts of unexplained jargon so I had to do the Rees's Potted Course on Collection, which involves getting on my hands and knees and raising and lowering my back. On paper, four simple diagrams explain the necessity of the horse changing his balance to recover his manoeuvrability, showing that he needs to bring his hind feet further forward under him, which requires raising the loin. I added some muscles so that she could see that draw reins, far from helping, break the neck in the middle and lock the loin. I showed her where this had contributed to his rigidity, and where they made him hurt in the poll and chest, so that he seemed ultra-sensitive there. We did it all six times in English and Spanish, writing down simple phrases until she said: "And so he needs to stretch because he's such a big boy, and when I don't let him he goes off bucking. So he needs to do it first by himself." Wow.

She rang me almost daily telling me how well he was going with this libertarian regime of warming up. "I look at your drawings every morning and I showed them to my teacher and he says you're not wrong." Jolly good.

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A year later, I was in the Canaries again, and went to see another "problem" horse in the same place. And there was Lena, leading the troll out of his coffin ready saddled and bridled, with the same rictus grin, the noseband digging into his nose, and the draw reins on.

"We found out what it was!" she cried. "It's his back and neck.“ She indicated the places I had shown her. "We've had to infiltrate all his joints there three times. I know you don't like draw reins but I put them on because he'll come out strong, he's been standing in the box for a month. We've had to do it three times!" She looked radiant.

I gave a lecture to the vet students, mentioning back problems and the necessity for a vet not simply to alleviate the pain but to have an eye for how the horse was worked so as to prevent a recurrence. "For instance, there's a horse near here… " A vet in the front started laughing and passing his hand over his face. Later he told me: "We're injecting cortisone into the joints." I nodded sadly.

"Yes, of course it doesn't help in the long run, He'll be crippled with arthritis in two years, and he's only six. But it means she can ride him now, so she wants it. It costs over a thousand every time we do it."

"But it was so simple. Don’t you see what I was getting at?"

"Oh, perfectly. But that was just it. Simple. Too simple.”

Some owners prefer to stand in the bar parroting technicalities about the exotic treatment their horses need, and how much it costs. Some owners like their horses immaculate every second of the day, even if they ache all over. Letting a horse loose to roll and frolic himself loose doesn't sound technical enough, like working him into an outline and using draw reins. It represents a heinous lack of control, which should always be firm and tight, like bleached bandages. And nobody can see what you’re doing if you just walk around on a loose rein bending and flexing: trotting's more impressive, especially if you're seen to be wrestling. Poor troll.

"You know what, you should charge more," said the vet, climbing into his new 4x4 while I walked back to the bus stop with that familiar feeling of being unable to cope with certain aspects of humanity.