‘And what are they?’ Tanner queried, examining the little brown tube with interest.

‘Costly rubies, rich and rare,’ his friend assured him. ‘They’re what we call “Muriquis,” and they’re made in Rio by a firm called Oliveira. There ain’t many in this village, I tell you. Who are you trailing now? Is it Henry Ford or only his Majesty the King?’

‘Neither,’ Tanner returned seriously, ‘it’s that Ponson case I’m on.’

‘Never heard of it. But Ponson knows his way about in cigarettes anyway, you bet your life.’

‘And how long since they were smoked? Can you tell me that?’

‘Nope. Not Tony B. This one about an hour; this one about a week at a guess. But don’t you take all you hear for gospel. I don’t know, as the girl said when her lover proposed.’

Tanner, though more bored with his friend’s conversation every time he met him, remained chatting for some minutes. The two men had been at school together, and the Inspector kept up the acquaintanceship because of the valuable information he frequently got on matters connected with tobacco. But as soon as possible he took his leave, breathing a sigh of relief when he found himself once more in the street.

His interest was considerably aroused by the news he had just received. The suspicions he had entertained of Cosgrove had been somewhat lulled to rest by the latter’s story. But the fact that the cigarette-end found in the boathouse at Luce Manor was of that same rare kind which Cosgrove smoked revived all his doubts, and made him more than ever resolved to test the alibi to the utmost limit of his ability.

Before leaving Halford, Tanner had written to the photographers whose names he had found on the prints in the drawing-room at Luce Manor, ordering copies of Sir William’s, Austin’s, and Cosgrove’s photographs. The studio was in Regent Street, and hailing a taxi, Tanner drove there. The photographs were ready, and he put one of each in his pocket. Also he selected prints of three or four other men as like in appearance to the cousins as he could find. Then he went on to the Duchess of Frothingham’s house in Park Lane.

He saw her Grace’s butler, and representing himself as a reporter on the staff of a well-known society journal, asked for a list of the guests present at the ‘At Home’ on the Wednesday of the murder, discreetly insinuating that he was prepared to pay for the trouble given. The addendum had the desired effect, and after a considerable delay a copy of the list was in Tanner’s hands. A glance at it showed Cosgrove’s name among the others, and a few judicious questions established the fact that he had actually been present.