“At least ringing has some scientific value,” she said. “ There’s some purpose to it. We know far more about migration and population patterns because of the ringing scheme. Twitching is just a game.”

“You’re quite right,” Rob Earl said. “ It’s all just a game.”

“Why don’t you cheat?” she asked. “If you were out on your own you could claim to have seen anything and nobody would know.”

“I would know,” Peter said. “Twitching is very competitive, especially if you’re going for a year list, but it’s still seeing the thing that counts, enjoying it for yourself, not describing it to somebody else.”

“What’s so special about a year list?”

“There’s something exciting about seeing how many birds you can see in Britain in one year. It’s a challenge.”

Rob stretched. “I only believe in a world list. Nothing else is the same.”

“But don’t people cheat?” Tina persisted. “What about stringers?”

“Stringers aren’t usually cheats. They don’t purposely fabricate. They’re just bad birders. They’re too optimistic. If they see a bird which might be a rarity, they claim it anyway. It doesn’t do them any good. Once you get a reputation as a stringer no one believes anything you see.”

Rob Earl was lying on his back on the floor, his rucksack under his head, a roll-up between his lips. Did he try to look like that, Adam wondered. Did he cultivate that Bob Dylan image with his beard, dark eyes and strange clothes? Rob lit a match by striking it against his thumbnail, and Adam decided that he did. Adam sat forward and prepared to speak, but Rob continued:

“It’s all a matter of ethics,” he said. “Twitchers’ ethics. Tom was a great believer in twitchers’ ethics, wasn’t he? We were always taking the piss. He had a rule for every occasion and no one ever took any notice.”

“I didn’t know Tom very well once he gave up ringing,” Tina said. “He was a good ringer. He always handled the birds so carefully. What sort of a twitcher was he?”

“He had too many principles,” Rob said. “When he lived up to them he was boring and when he didn’t he was guilty.”

“That’s very cruel,” she said. “ Didn’t you like him?”

“Yes, I liked him. But I never felt relaxed with him. He was too kind, too generous. It was as if he had such a low opinion of himself that he had to buy your friendship. He was never rude or bad-tempered.”

Peter was sitting by the window. There was no moon, but the stars were sharp and bright.

“The last time I saw Tom,” he said, “ was at a party on St. Mary’s, the autumn before last. He’d rented a whole cottage for himself and he had a party. As you say, he liked to make big, generous gestures. But I don’t think that he was buying friendship, he genuinely wanted people to have a good time. Like lots of twitchers, he didn’t have any social life outside birding. It was one of those magic evenings when everyone you meet is interesting or beautiful and they make you feel the same, and you drink enough but not too much, and the music is good. I had to leave before everyone else to get back to St. Agnes, Barbara and the milking. I looked for Tom to say goodbye, but I couldn’t find him.”