"Never," he replied; "though I will confess that I have suggested to him on numerous occasions the advisability of having a companion with him when he walked home late at night from the House. That, you remember, was a favourite habit of his. He used to say that the fresh air revived him after a long debate." "And he was quite right," I replied. "Now let us hear what the police have to say." The two members of the Detective Force, who had been detailed to take charge of the case, rose as we entered the room. They seemed somewhat surprised at seeing me, but upon my informing them how I came to be connected with the matter, willingly excused Mrs Castellan from attendance. "Do I understand you to say that you were the last of his friends to see Mr Castellan before his disappearance?" asked the taller of the two men, who looked more like a burly Yorkshire farmer than a member of the Scotland Yard Detective Force. "It would appear so," I replied. "We left Wiltshire House on hearing the news of the disaster to the _Sultan of Sedang_, drove to the Admiralty to learn the latest particulars, and then, having dismissed the carriage, strolled as far as Cockspur Street in each other's company." "And you parted at the passage that leads from Cockspur Street into Carlton House Terrace, I believe?" said the other man. "You did not happen to notice whether any person was following you, I suppose?" "I don't fancy either of us looked round during the whole distance," I answered, with an inward wish that I had been suspicious enough to have taken that simple precaution. "We had too much to occupy our thoughts without observing the actions of other people." "And how long did you remain on the pavement? I should be obliged if you would endeavour to be as accurate as possible, sir, in your answer to this question." I considered a moment before I replied. "Between eight and ten minutes I should say, certainly not more. I remember comparing my watch with a clock above the shop window at the corner, and remarking as I did so that I was nearly three minutes slow." "In that case you should be able to fix the time of his leaving you to within a minute or two," said the elder of the two men, taking a note-book and pencil from his pocket as he spoke. "I can do so exactly. It was five minutes past twelve when we bade each other good-night." "Was any one near you on the pavement while you were standing talking?" "No one, the street was almost deserted." "I notice that you say _almost_ deserted, sir. Then there were other people in sight. Do you happen to remember if any one was standing near you--that is to say, within fifty feet or so?"