‘Even when you had gone back into your bedroom? Did you go on talking to each other?’

‘He went on talking to me,’ corrected Mathilda.

‘Do you mean that you didn’t answer him?’

‘I said Oh! at intervals. Occasionally I said Yes, when he asked me if I was listening.’

‘Were you in the habit of talking to Mr Joseph while you were in your room, miss?’

‘I didn’t do it the night before, and I haven’t done it since, but three days isn’t really long enough for one to contract a habit, do you think?’

‘I see. And you came downstairs together on Christmas Eve?’

‘Arm in arm.’

‘Thank you, miss; that’s all I wanted to know,’ said Hemingway.

Stephen, who had been frowningly regarding him, said: ‘Just what are you driving at, Inspector?’

‘Checking up on my facts, sir, that’s all,’ Hemingway replied.

But when he saw Sergeant Ware, a few minutes later, he shook his head, and said: ‘No good. He took care to establish a cast-iron alibi all right.’

‘There you are, then!’ said the Sergeant, not altogether disappointed.

‘No, I’m not!’ Hemingway replied with some asperity. ‘On that evening, and on that evening only, Joseph made a point of holding forth to Miss Clare, while she was dressing for dinner, and if possible, I’m more than ever convinced that he’s the man I’m after.’

The Sergeant looked at him almost sadly. ‘I’ve never known you to go against the evidence before, sir.’

‘What you don’t see is that I haven’t got all the evidence. I’ve got a lot, but there’s a vital link which I’ve missed. Well, I can’t do any more until those lads ’phone through the result of developing that plate.’

‘Of course, if it does turn out to be a print of Joseph’s hand, it will be strong circumstantial evidence,’ conceded the Sergeant. ‘But not nearly strong enough, to my way of thinking, to convict him without our finding out how he could have got into Nathaniel’s room to murder him. What’s more, there’s still that handkerchief of Roydon’s.’

But Hemingway was plainly uninterested in Roydon’s handkerchief. While awaiting the telephone-call from the police-station, he was sought out by Valerie, who wanted to know whether she could go home. He assured her that he had not the least objection to her immediate departure, an announcement which greatly cheered her. She went off to persuade her mother to leave Lexham on the following morning, and found that that redoubtable lady had at last succeeded in cornering Stephen, and was manoeuvring for position. As she entered the drawing-room, she heard Mrs Dean say: ‘I know that you understood a mother’s anxiety, Stephen. I’m afraid I’m very, very jealous of my girlie’s happiness and future welfare. I could not have reconciled it with my conscience to have let the engagement continue as things were. But I’m sure you’re chivalrous enough to forgive a mother’s natural prudence.’

From the look on Stephen’s face this did not seem to be very probable. Before he could answer, Valerie said: ‘Oh, Mummy, I do wish you’d shut up! I keep on telling you I don’t want to marry Stephen! And anyway we can go home: that angelic Inspector says so.’