"Thank you, I'd love to," I said to Jackson, smiling at Isabella.

"Good," she said, smiling back.

"And thank you both for such a lovely evening on Thursday," I said. "I meant to bring you round a note."

"That's all right, don't bother," said Jackson. "It was a pleasure to have you. We all really enjoyed it." Unsurprisingly, he made no mention of his early departure from supper, nor his untimely row with Alex Reece.

"How's Alex?" I asked, perhaps unwisely.

"Alex?" he said, looking at me.

"Alex Reece," I said. "Your accountant."

"Oh, him," Jackson said, with a forced smile. "Bloody little weasel needs a good kick up the arse." He guffawed loudly.

"Really?" I said with mock sincerity. "I'll be needing an accountant soon myself. I thought I might go and see him. Are you saying I shouldn't?"

I was playing with him, and he suddenly didn't like it. The amusement evaporated from his eyes.

"Ask whoever you bloody like," he said dismissively.

As we climbed the few steps to the entrance to the Berkshire Stand we were joined by the Yorkes.

"Ah, the spy again," said Ewen, smiling.

I smiled back at him.

I found myself crammed into the lift with my back against the wall and with Julie Yorke standing far too close in front. Ewen would almost certainly have had a fit if he had realized that without any discernible sign to the others, she managed to slide her silk-sheathed firm and rounded buttocks back and forth across my groin in a manner guaranteed to excite.

By the time we arrived at the fourth floor I was glad to be able to pull my overcoat tight around me to save myself from major embarrassment. Julie smiled as I held the door of the box open for her, a seductive inviting smile with an open mouth and her tongue visible between her teeth.

"Come and see me sometime," she whispered in my ear as she went past.

I reckoned she must be crazy if she thought it was an invitation I was going to accept. Avoidance and evasion were definitely the names of the game here too. Jackson offered me a glass of champagne, and I took it out onto the balcony to watch the horses, and to escape from Julie Yorke.

"Do you think he'll win?" It was a moment before I realized that Rebecca Garraway was talking to me.

"Sorry?" I said.

"Do you think he'll win?" she repeated.

"Who?" I asked.

"Newark Hall, of course," she said. "Our horse."

I hadn't realized that the Garraways were Newark Hall's owners. I looked down at my race card, but it stated that the horse was owned by a company called Budsam Ltd.

"He has a good chance," I said back to her.

In truth, he had a better chance than she appreciated.

Ewen Yorke was standing to my left, looking through his large racing binoculars towards the two-and-a-half-mile start.

"Oh, hello," he said without lowering his binoculars. "Seems we have a problem."

"What problem?" Rebecca Garraway demanded with concern in her voice.

"It's OK," Ewen said, while still looking. "It's not Newark Hall, it's Scientific. Seems his reins have snapped. He's running away."

I looked down the course in horror, but without the benefit of Ewen's multi-magnification, I was unable to see exactly what was going on. I took a large gulp of my champagne. I should have asked Jackson for a whisky.

"Good. They've caught him," Ewen said, putting down his glasses. "No real harm done."

"So what will happen now?" I asked, trying hard to keep my voice as normal as possible. "Will Scientific be withdrawn?"

"Oh no, he'll run, all right, no problem. They'll just fit a new bridle on him down at the start," Ewen said. "The starter always has a spare, just in case something breaks. Indeed, just for situations like this. Most unlike your mother to have a tack malfunction." He almost laughed.

I felt sick. All that hard work with the scalpel, to say nothing about the expenditure of so much nervous energy since, and for what? Nothing. The horse would now run with perfect, uncut, unbreakable reins.

"That's good," I said, not actually thinking it was good for a second.

What, I wondered, would the blackmailer do if Scientific won?

I was doubly glad that I wasn't standing next to my mother on the owners' and trainers' stand. By now she would have become more of a head case than was usual. I just hoped she wasn't planning an Emily Davison suffragette-style dash out in front of her horse during the race to prevent it from winning. But in her present state of mind, I'd not put anything past her.

"They're off!" announced the public-address system, and all twelve runners moved away slowly, not one of the jockeys eager to set the early pace. They jumped the first fence without even breaking into a proper gallop, and only then did the horses gather pace and the race was on.

Even though I wanted to, I couldn't take my eyes off Scientific.

I suppose I was hoping he might have crossfired and cut into himself, but the horse appeared to gallop along easily, without any problems. Perhaps he would make an error, I thought, peck badly on landing, and unseat his rider.

But he didn't.

My mother had said that Scientific was a good novice but that the Game Spirit Steeplechase was a considerable step up in class. It didn't show. The horse jumped all the way around without putting a hoof wrong, and he was well placed in the leading trio as they turned into the finishing straight for the second and final time. The other two contenders were, as my mother had predicted they would be, Newark Hall and Sovereign Owner.

The three horses jumped the last fence abreast and battled together all the way to the finish line with the crowd cheering them on. Even the quiet, reserved Rebecca Garraway was jumping up and down, screaming encouragement, urging Newark Hall to summon up one last ounce of energy.

"Photograph, photograph!" announced the judge as the horses flashed past the winning post, each of them striving to get his nose in front.

No one in the box was sure which of the three had won.

Ewen Yorke and the Garraways rushed out to get to the winner's enclosure, confident that their horse had done enough, and Jackson went with them, leaving me in the box alone with Isabella and Julie.

"Do you think we won?" Julie asked, without much enthusiasm.

I was about to say that I had no idea when the public address announced, "Here is the result of the photograph. First number ten, second number six, third number eleven."

Number ten, the winner, was Scientific. He'd won by a short head from Newark Hall. Sovereign Owner had been third, another nose behind.

Oh shit, I thought.

"Oh, well," said Julie, shrugging her shoulders. "There's always next time. But Ewen will be like a caged tiger tonight, he hates so much to lose." She smiled at me again and raised her eyebrows in a seductive and questioning manner.

It wasn't Ewen, I thought, who was the caged tiger, it was his wife. And I had no desire to release her.

I watched on the television in the corner of the box as my mother greeted her winner, a genuine smile of triumph on her face. In the euphoria of victory, in the moment of ecstasy of beating Ewen Yorke, she had clearly forgotten that she had disobeyed the instructions of the man who might hold the keys to her prison cell.

It was too late to change anything now, I thought, so she might as well enjoy it while she could. Perhaps the stewards would find that Scientific had bumped into or somehow impeded one of the other horses.

But, of course, they didn't. And there were no objections, other than mine, and that wouldn't carry much authority with the stewards.

Scientific had won against the orders.

Only time would tell what the blackmailer thought.