“Also, look at the actual nature of this murder. It was a very nasty way to kill someone. There was a lot of hatred in whoever did this. It wasn’t done in a simple moment of anger or fear. The crime was vindictive; it had real unpleasantness in it, and a pretty gruesome irony in garroting her with a cello string. Talk about hoist with your own petard! If Margaret Macdonald was going to kill Lorna, she wouldn’t have murdered her like this. Their affair was dead, all passion spent far in the past. Margaret has lived for ages with the risk that Lorna might tell someone what had happened, and she made very sure that she lived a life whereby she could cope with the knowledge of that risk.”

Cordelia frowned and said, “But look at it this way. Probably the only thing that kept Lorna silent in the past was fear for her own reputation. But now it’s become rather fashionable to have had a bijou gay fling, so there was less need for her reticence. Surely the risk must have increased recently, and Margaret Macdonald must have realized that?”

“Not necessarily. I don’t think Margaret moves in that kind of world. And besides, why would she take a duffel-coat toggle from Longnor? She wouldn’t implicate Paddy, who’s supposed to be her best friend here.”

“Ah,” said Cordelia with satisfaction, “but at that stage she wouldn’t have specifically been incriminating Paddy, would she? She would just have been diverting suspicion away from herself in a general sort of way. We’ve probably got enough of a case against her to cast sufficient doubt on Paddy’s guilt to get the charges dropped, don’t you think?”

“But if we clear Paddy and don’t prove who really did it, people will always assume that it was Paddy. And I don’t really think Margaret, if she were the guilty party, would allow that state of affairs to continue.”

Cordelia thought for a moment and gnawed a chicken leg. Then she said, “You’re presuming too much on friendship. I don’t think I’d speak out to save a friend if my own freedom were at stake.”

“That’s very candid of you. And you’re probably right. Okay, leave Margaret in the running, but only as a rank outsider. Now, there’s James Cartwright. We’re cutting it rather fine as regards time, as well as assuming that he had access to a key to the music room. Not that that’s a very big assumption, given the amount of work he’s done there in the past. From their meeting in the afternoon he could have picked up that she’d be there again later. If we could only place him on the scene, we’d have a damn good case.”

“It would certainly be an excellent choice from the school’s point of view.” Cordelia remarked.