“What Mr. Ponson has told you is quite true, or at least almost. He was at my room at the Follies for about half an hour that evening, but not quite at the hour you have mentioned. He came about , and left at . I know the time because it is the only period in that play during which I am off the stage.”
She had avoided his trap anyway, and her answer confirmed Cosgrove’s story. But Tanner recognised he was dealing with a very clever woman, and he was by no means so convinced of the truth of her statement as he was of that of the butler. He went on:
“Obviously, madame, if we have to go before a jury the more corroborative evidence we can get the better. Now, are there any other persons who might have seen Mr. Ponson at the theatre, and who could be called to add their testimonies?”
“I don’t know if anyone else actually saw Mr. Ponson,” she answered, “but I should think it likely. Probably the doorkeeper did, or one of the other men. Have you made inquiries?”
“No, madame. Not yet.”
“Well, you had better do so,” and she got up to indicate that the interview was at an end.
Tanner found himself in the street with a baffled feeling of having handled the interview badly. But it was at least obvious that the lady’s advice was good, and somewhat ruefully he drove back to the Follies.
Here he made exhaustive inquiries, but without any very satisfactory result. The stage doorkeeper knew Cosgrove, and said he was a frequent visitor to Miss Belcher. He remembered he had come two or three evenings in the week in question at about , and stayed with the actress for about half an hour. But he could not be sure whether or not was one of these evenings. Three or four other attendants had also seen him, but in no case had there been anything to attract their attention to him, and none of them could say on what nights he had been there. But Tanner had to admit to himself that he could hardly expect such information from persons who were not interested in Cosgrove’s visit.
But on another point he got positive information. His inquiries established the fact that on the night of the murder Miss Belcher had been on the stage at . She therefore could not have been masquerading as Mrs. Franklyn’s servant at the Old Ferry.
On the whole the Inspector felt that, in spite of his momentary suspicion of Miss Belcher’s manner, he must fully accept the alibi. The evidence of Cosgrove’s missing the train, and travelling by the was overwhelming. The butler’s corroboration of his master’s return to Knightsbridge was convincing. Though Tanner was not so sure of Miss Belcher’s statement, it at least agreed with Cosgrove’s. Further, the lady had not fallen into Tanner’s little trap about the hour of the call and had disagreed with what he told her Cosgrove had said.
Then another point struck him. Cosgrove was at Knightsbridge between and , and at King’s Cross at . Was this evidence alone not sufficient? Would it have been possible for him to have visited Luce Manor in the interval? Suppose he had used a fast motor and gone by road?
Tanner did not think it could have been done. From London to Halford was thirty-five miles, and there and back made seventy. What speed could he reckon on? Considering how much of London would have to be traversed, and the amount of traffic to be expected on so important a road, Tanner felt sure not more than an average of thirty miles an hour at the outside. This would take two hours and twenty minutes at least, leaving from ten to twenty minutes. The motor never would have risked going up to Luce Manor, as it would have been heard—in fact, no motor did so. That meant that ten minutes must have been spent in going from the road to the boathouse, and another ten in returning. This even if it could be done at all, would leave no time in which to commit the murder, get out the boat and set the body and the oars adrift. Tanner considered it carefully, and at last came to the conclusion the thing would be utterly impossible. Indeed, he did not believe that an average of thirty miles an hour could be maintained. No, the alibi was complete. He felt he must unhesitatingly accept it.
Inspector Tanner was a depressed man as he walked slowly back to New Scotland Yard. Up to the present he saw that he had been on the wrong track—that all his time and trouble had been lost. He was now as far off solving the mystery, as when he started the inquiry, indeed further, for the real scent must now be cooler.
And Sergeant Longwell had been almost equally unsuccessful in his endeavour to trace the man who had made the fifth line of footprints on the river bank. With occasional assistance from Tanner the sergeant had made exhaustive inquiries in all the surrounding country, but without result. The only thing he had learnt which might have had a bearing on the matter was that a small, elderly man with a white goatee beard had taken the train from St. Albans to London, on the morning of the discovery of the crime. From Halford to St. Albans was about fifteen miles, and Longwell’s theory was that this man—if he were the suspect—had walked during the night to St. Albans, thinking that at a large station a considerable distance from Luce Manor he would be more likely to escape observation. But there was no real reason to connect this early traveller with the visitor to the boathouse. His boots had not been observed. But even if it had been proved that he was indeed
