"Does each horse have its own bridle?" I asked.

"They do on any given race day," Ian said. "But we have fifteen racing bridles in here, and they do for all our runners."

We were in the racing tack room. Apart from the bridles hanging on hooks, there was a mountain of other equipment, the most colorful being the mass of jockeys' silks hanging on a rail. There were also two boxes of special bits, and others of blinkers, visors, cheek pieces and sheepskin nosebands. Up against the far wall, on top of a sort of sideboard, there were neat stacks of horse blankets, weight cloths and under-saddle pads, and there was even a collection of padded jackets for the stable staff to wear in the parade ring.

"So, say on Saturday, when Scientific runs at Newbury," I said. "Can you tell which bridle he'll use?"

Ian looked at me strangely. "No," he said. "Jack will take any one of these." He waved a hand at the fifteen bridles on their hooks.

To be honest, that wasn't the most helpful of answers.

"Don't any of the horses have their own bridle?" I asked, trying not to sound desperate.

"One or two," he said. "Old Perfidio has his own. That's because he has a special bit to try and stop him from biting his tongue during the race."

"But doesn't sharing tack result in cross-contamination?" I said.

"Not that we've noticed. We always dip bridles in disinfectant after every use, even the regular exercise ones."

I could see that making Scientific's bridle or reins break on Saturday in the Game Spirit Steeplechase was not going to be as easy as I had imagined, at least not without Ian or Jack knowing about it.

"How about special nosebands?" I asked. "Why, for example, do some horses run in sheepskin nosebands?"

"Some trainers run all their horses in sheepskin nosebands," Ian said. "It helps them to see which horse is theirs. The colors aren't very easy to see when the horses are coming straight at you, especially if it's muddy."

"Do my mother's horses all wear them?"

"No," he said. "Not as a general rule. But we do use them occasionally if a horse tends to run with his head held up."

"Why's that?"

"If a horse runs with his head too high he isn't looking at the bottom of the fences, and also when the jockey pulls the reins the horse will lift it higher, not put it down like he should. So we put a nice thick sheepskin on him and he has to lower his head a little to see where he's going."

"Amazing," I said. "Does it really work?"

"Of course it works," he said, almost affronted. "We wouldn't do it if it didn't work. We also sometimes put cross nosebands on them to keep their mouths shut, especially if they're a puller. Keeping their mouths closed often stops them from pulling too hard. Or an Australian noseband will lift the bit higher in the mouth to stop a horse from putting his tongue over it."

"Is that important?" I asked.

"It can be," Ian said. "If a horse puts his tongue over the bit it can push on the back of the mouth and put pressure on the airway so the horse can't breathe properly."

There was clearly so much I didn't know about racehorse training.

I think you might have to revert to the liquidized green potato peel," I said to my mother when I went back into the kitchen.

"Why?" she said.

"Because I can't see how we are going to arrange for Scientific's reins to break during the race on Saturday if we can't even be sure which bridle he'll be wearing."

"I'll ask Jack," she said.

"That might be a bit suspicious," I said. "Especially after the race. Much better if we can be sure ahead of time which bridle he'll be wearing. Can't you run him in a sheepskin noseband?"

"That won't help," she said. "We simply fit the sheepskin to a regular bridle using Velcro."

"Can't you think of anything?" I asked, not quite in desperation. "How about a cross or an Australian noseband?"

"He could run in an Australian, I suppose. That would mean he would have to have the one bridle we have fitted with it."

"Good," I said. "But you'll have to show me."

"What, now?"

"No, later, when Ian and Jack have gone," I said. "And make sure Scientific is the only horse this week that runs in it."

The phone rang. My mother walked across the kitchen and picked it up.

"Hello," she said. "Kauri House."

She listened for a moment.

"It's for you," she said, holding the telephone out towards me. I thought I detected a touch of irritation in her voice.

"Hello," I said.

"Hi, Tom. Would you like to come to supper tomorrow night?" It was Isabella.

"I thought you were cross with me," I said.

"I am," she replied bluntly. "But I always invite people I'm cross with to supper. Have you tasted my cooking?"

I laughed. "OK, I'll chance it. Thanks."

"Great. Seven-thirty or thereabouts, at the Hall."

"Black tie?" I asked.

"Absolutely," she said, laughing. "No, of course not. Very casual. I'll be in jeans. It's just a kitchen supper with friends."

"I'll bring a bottle."

"That would be great," she said. "See you tomorrow."

She disconnected, and I handed the phone back to my mother, smiling.

"I don't know why you want to associate with that woman," she said in her most haughty voice. She made it sound as though I was fraternizing with the enemy.

I wasn't in the mood to have yet another argument with her over whom I should and should not be friends with. We had done enough of that throughout my teenage years, and she had usually won by refusing entry to the house for my friends of whom she hadn't approved, which, if I remembered correctly, had been most of them.

"Are you going to the races today?" I asked her instead.

"No," she replied. "I've no runners today."

"Do you only go to the races if you have a runner?" I asked.

She looked at me as if I was a fool. "Of course."

"I thought you might go just for the enjoyment of it," I said.

"Going to the races is my job," she said. "Would you do your job on days you didn't have to, just for the enjoyment?"

Actually, I would have, but there again, I enjoyed doing the things others might have been squeamish about.

"I might," I said.

"Not to Ludlow or Carlisle on a cold winter Wednesday, you wouldn't." She had a point. "It's not like Royal Ascot in June."

"No," I agreed. "So you can show me which bridle Scientific will use after lunch when the stable staff are off."

"Do you really think you can make the reins break during the race?" she asked.

"I had a good look at them," I said. "I think it might be possible."

"But how?"

"The reins are made of leather, but they have a nonslip rubber covering sewn round them, like the rubber on a table-tennis bat but with smaller pimples." She nodded. "The rubber is thin and not very strong. If I was able to break the leather inside the rubber, then it wouldn't be visible, and the reins would part during the race when the jockey pulls on them."

"It seems very risky," she said.

"Would you rather use your green-potato-peel soup?" I asked.

"No," she said adamantly. "That would ruin the horse forever."

"OK," I said. "You show me which bridle Scientific will wear, and I'll do the rest."

Was I getting myself in too deep here?

Was I about to become an accessory to a fraud on the betting public as well as to tax evasion?

Yes. Guilty on both counts.