When I was about 11 or 12, Mr O, who owned the stables and trekking centre I haunted at weekends and school holidays, sensing a potential lucrative market for experienced adult horse-riders, brought home two ex-racehorses from the auctions. Sleek, attenuated English Thoroughbreds with legs and necks that went on forever, finely-veined faces and large intelligent eyes. A pair of glamorous, highly-strung supermodels introduced to the common herd of solid, stolid unpedigree'd ponies.

Whether he was deluding himself they might turn out to be handy on the hill trails, or whether Mr O just secretly wanted an excuse to have a couple of fine horses, inevitably they were a total failure as trekking horses. They abhored the mud, missed their footing while tip-toeing over rough ground, hated being held to a steady pace. Baby, they were born to run.

Robineau was the one that I befriended. He was a handsome bay gelding, retired after a life of only very modest success as a hurdler. I was a small skinny kid, and at 17 hands tall my heels only came half-way down his sides. He was bossy and domineering, prone to bullying the other horses, fiercely intolerant of chickens and goats, and devoted to the stable cat, Miss Fluff. Miss Fluff not only slept on Robby's back, but even safely delivered a litter of kittens in his stall and he never stepped on a single one of them.

Unsurprisingly, Robby was fast. He launched from a standing start like a rocket and viewed any area of open grass as an invitation to stretch his neck and run. The best thing to do was just hang on for the ride and trust him. I only had one fall from him, and that was when he took a corner at full gallop and I carried straight on. No harm done, except to the pride. Then one day I went to the stables and he was gone. Sold to someone who had fallen in love with his cranky personality just as much as I had. Well, he deserved a happy retirement, he was a beautiful horse with a big heart. But I often wondered if he missed Miss Fluff in his new home.

The other ex-racehorse Mr O had brought home that day was very different. A bright chestnut mare, at only 15.2 hands and with a petite build, she had proved neither temperamentally nor physically fit for the track, and more than justified the Thoroughbred reputation for being "a bit difficult". Her name was Psyche, but within days her stable-name was Psycho. She was headstrong and unruly, she kicked and bit anyone she could reach, she fought her rider and spooked at her own shadow. We kids weren't allowed in her stall, and she was ridden only by Mr O and one or two of the most experienced regular riders.

One day, one of these trusted riders, a very competant lady I will call Mrs Gee, rode out with Psycho. Barely an hour later, we heard the news we'd all been subconsciously waiting for since the day Psycho arrived. She had spooked at something in the roadside verge and leapt into oncoming traffic. Mrs Gee escaped with a broken collar bone from falling onto the tarmac. Psyche was hit by a car, and brought home with a thick triangular flap of flesh and skin hanging from her forearm. She was sedated, but I had never seen such pain in a horse's eyes, and I never want to again.

Psyche recovered, but she was never quite the same as she had been before the accident. She carried a hideous scar of course, and favoured her right foreleg when tired, but it was her personality that seemed to have undergone a sea-change. Unlike the traumatized horse Pilgrim in The Horse Whisperer, who became wild and violent after his accident, Psyche became - well, not quite docile, but manageable. She was still nervy but no longer deliberately mean. Mr O kept her, I think partly because he felt somehow responsible for her injury, and partly because he was genuinely fond of her by then. When I left home some six years or so later, he still had her.

So both horses had a happy end to their story. That's not the case for many retired racehorses. Because of their experiences and temperament they can be difficult to retrain as pleasure riding horses or for a second career. A few very lucky ones might find a place in a rest home when their competitive days are over, but the vast majority quietly disappear into silence - slaughtered for pet food. And that's why I wanted to write about Robby and Psyche, to give you something to think about the next time you cheer on the big-hearted horse winning a few pounds for you in the 3.30 at Ascot.