“You know that you must tell the police,” George said.

“What would they do? Take him to the police station for questioning. They might frighten him into saying something, but I doubt it. He’s stubborn.”

“He could not deny the letter.”

“It could all be quite innocent.”

“Yes. It could be.”

“While we’ve been talking, I have been thinking,” she said. She was unused to asking for help. “It has occurred to me that you might see him, talk to him, make up your own mind about it. Then, if you think that there is anything suspicious, take the letter to the police. But find out first. The police will not get to the truth of the matter. If he is innocent all the publicity would destroy him, and his wife. If he is guilty, I have no faith in the police’s ability to bring him to justice.”

George did not answer directly. “ I wonder,” he said, “ what it is that Charlie would have used against him. Do you have any idea?”

“I thought perhaps another letter. Paul Derbyshire doesn’t seem to have taken great care to destroy the evidence.”

“Charlie would hardly have been in a position to check through the waste-paper bins in the observatory bedrooms.”

“You obviously did not know Charlie.”

He changed the subject quite suddenly. “Did you know that there was chloroform in the ringing-room cupboard?”

“Yes. Everyone must have seen it there. Some of the teachers who bring school groups to the island seem to be extremely careless about equipment. It would not have happened in my school.”

He stood up and looked again out of the window.

“I’ll do as you say,” he said. “ I’ll go and talk to Derbyshire. It won’t be an easy interview. Then, if I feel that it’s necessary, I’ll go to the police.”

She smiled. “Thank you,” she said. “That will do very well.”

“I want to get everyone on to the island again,” he said. “ Perhaps on Friday. Do you think that they will come?”

“I will come,” she said. “You must ask the others.”

“I’ll ask John to meet you with the Land Rover.” “And I’ll be hoping for a north-westerly gale.”

George was late for the meeting with Molly at the quay, but he was still there before her. Usually he was irritated by her lack of punctuality, but now he was glad of the opportunity to be alone. Besides, he had waited for her so often that he would have been disappointed if she had been on time. The late-afternoon sun was warm. He sat, like a boy, on the edge of the quay with his legs dangling over the mud. Waders were feeding on the shore in huge numbers, and as he watched them through his binoculars, he emptied his mind of the island and of questions and suspicion and fear. It had always been the only way he could force himself to unwind. While he was counting the birds there was a movement across the mud. The birds started to call, rose in a group in alarm. A peregrine dropped from the sun, took one of the foolish, flapping creatures and flew with it across the estuary to the hills. The incident was over in seconds, but for George it was a joy, a reward to sustain him.