During the run-up to the conspiracy trial, the police had done their best to unravel his background further, but Julius Apollo knew a thing or two about off-shore companies and had stayed comfortably ravelled. He still officially lived on the Isle of Man, though he was never there for long. During the Flat season he mostly divided his time between hotels in Newmarket and Paris, and in the winter he dropped entirely out of sight, as far as the Security Service was concerned. Steeplechasing, the winter sport, never drew him.

During my first summer with the Service he had bought, to everyone's surprise, one of the most promising two-year-olds in the country. Surprise, because the former owner, Ezra Gideon, was one of the naturals aristocrats of racing, a much respected elderly and extremely wealthy man who lived for his horses and delighted in their successes. No one had been able to persuade him to say why he had parted with the best of his crop or for what price: he bore its subsequent high-flying autumn, its brilliant three-year-old season and its eventual multi-million-pound syndication for stud with an unvaryingly stony expression.

After Filmer's acquittal, Ezra Gideon had again sold him a two-year-old of great promise. The Jockey Club mandarins begged Gideon practically on their knees to tell them why. He said merely that it was a private arrangement: and since then he had not been seen on a racecourse.

On the day Derry Welfram died I drove homewards to London wondering yet again, as so many people had wondered so often, just what leverage Filmer had used on Gideon. Blackmailers had gone largely out of business since adultery and homosexuality had been blown wide open, and one couldn't see old-fashioned upright Ezra Gideon as one of the newly fashionable brands of transgressor, an insider-trader or an abuser of children. Yet without some overwhelming reason he would never have sold Filmer two such horses, denying himself what he most enjoyed in life.

Poor old man, I thought. Derry Welfram or someone like that had got to him, as to the witnesses, as to Paul Shacklebury dead in his ditch. Poor old man, too afraid of the consequences to let anyone help.

Before I reached home the telephone again purred in my car and I picked up the receiver to hear Millington 's voice.

'The boss wants to see you,' he said. 'This evening at eight, usual place. Any problem?'

'No,' I said. 'I'll be there. Do you know… er… why?'

'I should think,' Millington said, 'because Ezra Gideon has shot himself.'

The boss, Brigadier Valentine Catto, Director of Security to the Jockey Club, was short, spare, and a commanding officer from his polished toecaps to the thinning blond hair on his crown. He had all the organizational skills needed to rise high in the army, and he was intelligent and unhurried and listened attentively to what he was told.

I met him first on a day when old Clement Cornborough asked me again to lunch to discuss in detail, as he said, the winding up of the Trust he'd administered on my behalf for twenty years. A small celebration, he said. At his club.

His club turned out to be the Hobbs Sandwich Club, near the Oval cricket ground, a Victorian mini-mansion with a darkly opulent bar and club rooms, their oak-panelled walls decorated with endless pictures of gentlemen in small cricket caps, large white flannels and (quite often) side-whiskers.

The Hobbs Sandwich, he said, leading the way through stained-glass panelled doors, was named for two great Surrey cricketers from between the wars, Sir Jack Hobbs, one of the few cricketers ever knighted, and Andrew Sandham, who had scored one hundred and seven centuries in first-class cricket. Long before I was born, he said.

I hadn't played cricket since distant days at school, nor liked it particularly even then: Clement Cornborough proved to be a lifelong fanatic.

He introduced me in the bar to an equal fanatic, his friend Val Catto, who then joined us for lunch. Not a word about my Trust was spoken. The two of them talked cricket solidly for fifteen minutes and then the friend Catto began asking questions about my life. It dawned on me uneasily after a while that I was being interviewed, though I didn't know for what; and I learned afterwards that in conversation one day during the tea interval of a cricket match Catto had lamented to Cornborough that what he really needed was someone who knew the racing scene intimately, but whom the racing scene didn't know in return. An eyes and ears man. A silent, unknown investigator. A fly on racing's wall that no one would notice. Such a person, they had sighed together, was unlikely to be found. And that when a few weeks later I walked into Cornborough's office (or at least by the time I left it) the lawyer had suffered a brainwave which he passed on to his friend Val.

The Hobbs Sandwich lunch (of anything but sandwiches) had lasted through a good chunk of the afternoon, and by the end of it I had a job. I hadn't taken a lot of persuading, as it seemed interesting to me from the start. A month's trial on both sides. Brigadier Catto said, and mentioned a salary that had Cornborough smiling broadly.

'What's so funny?' the Brigadier asked. 'That's normal. We pay most of our men that at the start.'

'I forgot to mention it. Tor here is… um…' He paused, perhaps wondering whether finishing the sentence came under the heading of breaking a client's right to confidentiality, because after a short while he went on, 'He'd better tell you himself.'

'I accept the salary,' I said.

'What have you not told me?' Catto asked, suddenly very much the boss, his eyes not exactly suspicious but unsmiling: and I saw that I was not binding myself to some slightly eccentric friendly cricket nut, but to the purposeful, powerful man who had commanded a brigade and was currently keeping horseracing honest. I was not going to be playing a game, he was meaning, and if I thought so we would go no further.

I said wryly, 'I have a private income after tax of about twenty times the salary you're offering, but I'll take your money all the same, sir, and I'll work for it.'

He listened to the underlying declaration of commitment and good faith, and after a long pause he smiled briefly and nodded.

'Very well,' he said. 'When can you start?’

I had started the next day at Epsom races, relearning the characters, reawakening sleeping memories, hearing Aunt Viv's bright voice in my ear about as clearly as if she were alive. 'There's Paddy Fredericks. Did I tell you he used to be married to Betsy who's now Mrs Glovebinder? Brad Glovebinder used to have horses with Paddy Fredericks but when he pinched Betsy, he took his horses away too… no justice in the world. Hello Paddy, how are things? This is my nephew Torquil, as I expect you remember, you've met him often enough. Well done with your winner, Paddy…' and Paddy had taken us off for a drink, buying me a Coke.

I came face to face unexpectedly with the trainer Paddy Fredericks that first day at Epsom and he hadn't known me.

There hadn't been a pause or a flicker. Aunt Viv had been dead nearly eight years and I had changed too much; and I had been reassured from that early moment that my weird new non-identity was going to work.

On the grounds that racing villains made it their business to know the Security Service comprehensively by sight, Brigadier Catto said that if ever he wanted to speak to me himself, it would never be on a racecourse but always in the bar of the Hobbs Sandwich, and so it had been for the past three years. He and Clement Cornborough had sponsored me for full membership of the club and encouraged me to go there occasionally on other days on my own, and although I'd thought the Brigadier's passion for secrecy a shade obsessive I had fallen in with his wishes and come to enjoy it, even if I'd learned a lot more about cricket than I really wanted to.