“This week, I discovered that the murder was committed in such a way that it required certain preparations to be made in advance, made, in fact, at about the time you were dropping Caroline off after your afternoon out . . . Obviously the police have questioned most of the people who were around at the time but I don’t think they’ve gone to the lengths I have because they were sure they had the person responsible. I just wondered if you had seen anything unusual.”

“I see,” he said, seeming to relax. “By the way, I’m not being very hospitable. Would you like a drink?”

“No thanks, I’ve got the car,” said Lindsay, glad of the excuse not to accept a drink from a man she still feared could be a murderer. “Now, when you dropped Caroline off, what exactly did you do, can you remember?”

“We got to Derbyshire House about half-past five—quarter to six—that sort of time. I drove her up to Longnor House in the Daimler. I got out with her and went up to her room to collect some family photographs and came down more or less right away, because it was nearly time for her to have dinner. Then I drove back to my hotel.”

“Did you go straight back to the hotel?”

“Of course I did! When I got there, I sat in the car for about half an hour listening to the end of a Bartok concert on the radio.”

“You misunderstood me,” said Lindsay, congratulating herself that she was beginning to get somewhere on establishing opportunity. “I meant, did you come straight down the drive the way you came in, or did you by any chance drive round by the building site?”

“The building site? Oh, you mean where they’re putting up the squash courts? No, why on earth should I have? They’re way beyond the trees. I suppose it might have been logical to turn left and go round the back of the house to rejoin the main drive but I simply went right, back the way I’d come. It was more or less dark by then and there were quite a lot of girls going off to dinner. I didn’t want to chance hitting any of them with the car, so I avoided the back of the main building as far as possible. Does that answer your question?”

“Yes, thank you. You were aware of what was happening at the school that night, weren’t you?”

“Caroline had mentioned the concert, yes.”

“I’m surprised you didn’t stay for it, since you seem to enjoy music enough to sit in the car on a cold night, listening to the end of a piece of Bartok,” said Lindsay casually.

He looked sharply at her. “I had a lot of work to do. And besides, the program didn’t appeal to me,” he retorted.