I played poker with the children and lost to Henry because half my mind was occupied with his father's affairs.

Henry said, 'You aren't thinking what you're doing, Alan,' in a mock sorrowful tone as he rooked me of ten chips with two pairs.

'I expect he's in love,' said Polly, turning on me an assessing female eye. There was that, too.

'Pooh,' said Henry. He dealt the cards.

'What's in love?' said William, who was playing tiddly-winks with his chips, to Henry's annoyance.

'Soppy stuff,' said Henry. 'Kissing, and all that slush.'

'Mummy's in love with me,' said William, a cuddly child.

'Don't be silly,' said Polly loftily, from her eleven years. 'In love means weddings and brides and confetti and things.'

'Well, Alan,' said Henry, in a scornful voice, 'you'd better get out of love quick or you won't have any chips left.'

William picked up his hand. His eyes and mouth opened wide. This meant he had at least two aces. They were the only cards he ever raised on. I saw Henry give him a flick of a glance, then look back at his own hand. He discarded three and took three more, and at his turn, he pushed away his cards. I turned them over. Two queens and two tens. Henry was a realist. He knew when to give in. And William, bouncing up and down with excitement, won only four chips with three aces and a pair of fives.

Not for the first time I wondered at the quirks of heredity. Bill had been a friendly, genuine man of many solid virtues. Scilla, matching him, was compassionate and loving. Neither was at all intellectually gifted; yet they had endowed their elder son with a piercing, exceptional intelligence.

And how could I guess, as I cut the cards for Polly and helped William straighten up his leaning tower of chips, that Henry already held in his sharp eight-year-old brain the key to the puzzle of his father's death.

He didn't know it himself.

The Cheltenham National Hunt Festival meeting started on Tuesday, 2 March.

Three days of superlative racing lay ahead, and the finest 'chasers in the world crowded into the racecourse stables. Ferries from Ireland brought them across by boat and plane load; dark horses from the bogs whose supernatural turn of foot was foretold in thick mysterious brogue, and golden geldings who had already taken prizes and cups galore across the Irish Sea.

Horse-boxes from Scotland, from Kent, from Devon, from everywhere, converged on Gloucestershire. Inside, they carried Grand National winners, champion hurdlers, all-conquering handicappers, splendid hunters: the aristocrats among jumpers.

With four big races in the three days reserved for them alone, every amateur jockey in the country who could beg, borrow, or buy a mount hurried to the course. A ride at Cheltenham was an honour: a win at Cheltenham an experience never to be forgotten. The amateur jockeys embraced the Festival with passionate fervour.

But one amateur jockey, Alan York, felt none of this passionate fervour as he drove into the car park. I could not explain it to myself, but for once the hum of the gathering crowd, the expectant faces, the sunshine of the cold invigorating March morning, even the prospect of riding three good horses at the meeting, stirred me not at all.

Outside the main gate I sought out the newspaper seller I had spoken to at Plumpton. He was a short, tubby little Cockney with a large moustache and a cheerful temperament. He saw me coming, and held out a paper.

'Morning, Mr York,' he said. 'Do you fancy your horse today?'

'You might have a bit on,' I said, 'but not your shirt. There's the Irishman to be reckoned with.'

'You'll do him, all right.'

'Well, I hope so.' I waited while he sold a newspaper to an elderly man with enormous race glasses. Then I said, 'Do you remember the taxi-drivers fighting at Plumpton?'

'Couldn't hardly forget it, could I?' He beamed.

'You told me one lot came from London and one from Brighton.'

'Yes, that's right.'

'Which lot were which?' I said. He looked mystified.

I said, 'Which lot came from London and which came from Brighton?'

'Oh, I see.' He sold a paper to two middle-aged ladies wearing thick tweeds and ribbed woollen stockings, and gave them change. Then he turned back to me.

'Which lot was which, like? Hm- I see 'em often enough, you know, but they ain't a friendly lot. They don't talk to you. Not like the private chauffeurs, see? I'd know the Brighton lot if I could see 'em, though. Know 'em by sight, see?' He broke off to yell 'Midday Special' at the top of his lungs, and as a result sold three more papers. I waited patiently.

'How do you recognize them?' I asked.

'By their faces, o'course.' He thought it a foolish question.

'Yes, but which faces? Can you describe them?'

'Oh, I see. There's all sorts.'

'Can't you describe just one of them?' I asked.

He narrowed his eyes, thinking, and tugged his moustache. 'One of 'em. Well, there's one nasty-looking chap with sort of slitty eyes. I wouldn't like a ride in his taxi. You'd know him by his hair, I reckon. It grows nearly down to his eyebrows. Rum-looking cove. What do you want him for?'

'I don't want him,' I said. 'I just want to know where he comes from.'

' Brighton, that's it.' He beamed at me. 'There's another one I see sometimes, too. A young ted with sideboards, always cleaning his nails with a knife.'

'Thanks a lot,' I said. I gave him a pound note and his beam grew wider. He tucked it into an inside pocket.

'Best of luck, sir,' he said. I left him, with 'Midday Special' ringing in my ears, and went in to the weighing room, pondering on the information that my captors with the horse-box came from Brighton. Whoever had sent them could not have imagined that I had seen them before, and could find them again.

Preoccupied, I suddenly realized that Pete Gregory was talking to me. '- Had a puncture on the way, but they've got here safely, that's the main thing. Are you listening, Alan?'

'Yes, Pete. Sorry. I was thinking.'

'Glad to hear you can,' said Pete with a fat laugh. Tough and shrewd though he was, his sense of humour had never grown up. Schoolboy insults passed as the highest form of wit for him; but one got used to it.

'How is Palindrome?' I asked. My best horse.

'He's fine. I was just telling you, they had a puncture-' He broke off, exasperated. He hated having to repeat things. 'Oh well- do you want to go over to the stables and have a look at him?'

'Yes, please,' I said.

We walked down to the stables. Pete had to come with me because of the tight security rules. Even owners could not visit their horses without the trainer to vouch for them, and stable boys had passes with their photographs on, to show at the stable gate. It was all designed to prevent the doping or 'nobbling' of horses.

In his box I patted my beautiful 'chaser, an eight-year-old bay with black points, and gave him a lump of sugar. Pete clicked his tongue disapprovingly and said, 'Not before the race,' like a nanny who had caught her charge being given sweets before lunch. I grinned. Pete had a phobia on the subject.

'Sugar will give him more energy,' I said, giving Palindrome another lump and making a fuss of him. 'He looks well.'

'He ought to win if you judge it right,' said Pete. 'Keep your eyes on that Irishman, Barney. He'll try to slip you all with a sudden burst as you go into the water so that he can start up the hill six lengths in front. I've seen him do it time and again. He gets everyone else chasing him like mad up the hill using up all the reserves they need for the finish. Now, either you burst with him, and go up the hill at his pace and no faster, or, if you lose him, take it easy up the hill and pile on the pressure when you're coming down again. Clear?'