“What is the problem, precisely?” he asked, facing his attention back to the room. “You’d like us to trace your son?”

“That’s right!” The man’s voice was sharp and irritable. “He’s been missing for months. We hear about him occasionally, and sometimes he phones up to tell his mother he’s all right, but he moves around a lot, and we never know where he is.”

“Is there any special reason for wanting to trace him now?” George asked.

“It was Muriel’s idea,” Franks said angrily. “She thought it was the right thing to do. I want to sell the business, and she thinks the lad should be consulted before I go ahead. I told her there’s no chance that he’d want to come back here and work for the family. He made that quite clear when he left home. I’m not sure what she’s doing. I think it’s only an excuse to get him home. She misses him.”

He spoke as if this were some unaccountable weakness.

Molly watched him curiously.

“What is your business?” she asked, and realised at once that it had been the right question. He spoke to her directly for the first time.

“Franks’ Meat Products,” the man said with pride. “We make sausage skins. They’re famous in the trade. I’ve been offered a very good price.”

“Who advised you to contact us?” George asked. Before his retirement he had worked as a civil servant with the Home Office. More recently he and his wife had started an enquiry agency. They were based in Surrey, and though they received referrals occasionally from solicitors in other parts of the country, it was unusual to be contacted by an unknown member of the public. They never advertised their services.

“No one advised me,” Franks said. He seemed surprised. “ I heard about you from Gregory, of course, when he was still at home. You’re a birdwatcher, aren’t you? You must have heard of our Gregory. I understand that he’s something of a celebrity in his own field.”

“Of course,” George said. “Greg Franks. Yes, of course.”

And he was taken back immediately to the hide in Northumberland, and the memory of the incident with the Baillon’s crake returned to him with astonishing clarity.

He was still absorbed in the daydream when Muriel Franks came in carrying a tray. She was small, nervous, sharp-featured, quite determined, it seemed, that she would get her own way.

“You will help us find Gregory, won’t you Mr. Palmer-Jones?” she said.