Suppose again that blackmail had been levied, where did Austin and Cosgrove come in? They must in this case obviously have taken sides. Either they must have been assisting Sir William to extricate himself, or else they must have been party to the blackmail.

But as Tanner pondered these alternatives, he could not see how either would meet the facts. If the cousins were acting for their relative, they obviously would not have murdered him—it was a contradiction in terms. Here again the wrong man had been killed.

On the other hand, it was difficult to see how they could have been in league with Douglas against Sir William. Anything discreditable to the manufacturer would react on both the son and nephew, and their threat to make the matter public would therefore hardly be convincing. For their own sakes the cousins would be as anxious as Sir William to keep the thing quiet. It was also clear to Tanner that they would never have put themselves in the power of a man like Douglas. If they had wished to murder Sir William for his money, they would have done so at some time when Douglas would not have witnessed the crime.

So far had Tanner progressed when he realised his argument really was that Sir William could not have been murdered at all! He swore angrily, and went back to see the point from which he had started. Blackmail. It would seem, then, that blackmail could not be the explanation. And yet … It was an attractive theory …

Some days later, rather to Tanner’s surprise, he received from a sergeant of police in the north of England an answer to his circular about the photograph. It read:

Sir: We have found the churchyard illustrated in your view attached. It belongs to the Parish Church of Tynwick, a village six miles south-east of Gateshead. The headstone is still standing. It bears the inscription—“Sacred to the memory of John Dale, aged 53, who departed this life on 4th September 1871, and of Eleanor, his beloved wife, who entered into rest on 25th March 1890, at the age of 67.” ’

‘Gateshead? Dale?’ thought the Inspector. ‘Those names sound familiar.’

He turned to his notes of the case. And then he got rather a thrill. Gateshead was the place from which Sir William had come to Luce Manor. It was there the deceased gentleman had been born and had spent his life, and where the ironworks he had owned was situated.

And Dale? This was more interesting still. Dale was the name of his wife’s first husband! He had married a Mrs Ethel Dale. Here at last was a connection between the manufacturer and William Douglas.

But after all was it not a very slender one? What exactly did it amount to? That Douglas had in his possession a photograph of the grave of a man and woman of the same name as Lady Ponson’s first husband, and who lived somewhere in the same locality. Not much to go upon, and yet it was suggestive, and where there had been nothing before, Tanner welcomed it eagerly. Who knew what it mightn’t lead to? He determined he must go to Tynwick and make inquiries.