“Very remarkable,” mused Marchmont; “most remarkable.  But, perhaps, you can tell us, Dr. Thorndyke, who this woman was?”

“I think,” replied Thorndyke, “that the next item of evidence will enable you to form an opinion for yourselves.  I only obtained it yesterday, and, as it made my case quite complete, I wrote off to you immediately.  It is the statement of Joseph Ridley, another cabman, and unfortunately, a rather dull, unobservant fellow, unlike Wilkins.  He has not much to tell us, but what little he has is highly instructive.  Here is the statement, signed by the deponent and witnessed by me: 

“’My name is Joseph Ridley.  I am the driver of a four-wheeled cab.  On the fourteenth of March, the day of the great fog, I was waiting at Vauxhall Station, where I had just set down a fare.  About five o’clock a lady came and told me to drive over to Upper Kennington Lane to take up a passenger.  She was a middle-sized woman.  I could not tell what her age was, or what she was like, because her head was wrapped up in a sort of knitted, woollen veil to keep out the fog.  I did not notice how she was dressed.  She got into the cab and I led the horse over to Upper Kennington Lane and a little way up the lane, until the lady tapped at the front, window for me to stop.

“’She got out of the cab and told me to wait.  Then she went away and disappeared in the fog.  Presently a lady and gentleman came from the direction in which she had gone.  The lady looked like the same lady, but I won’t answer to that.  Her head was wrapped up in the same kind of veil or shawl, and I noticed that she had on a dark coloured mantle with bead fringe on it.

“’The gentleman was clean shaved and wore spectacles, and he stooped a good deal.  I can’t say whether his sight was good or bad.  He helped the lady into the cab and told me to drive to the Great Northern Station, King’s Cross.  Then he got in himself and I drove off.  I got to the station about a quarter to six and the lady and gentleman got out.  The gentleman paid my fare and they both went into the station.  I did not notice anything unusual about either of them.  Directly after they had gone, I got a fresh fare and drove away.’

“That,” Thorndyke concluded, “is Joseph Ridley’s statement; and I think it will enable you to give a meaning to the other facts that I have offered for your consideration.”

“I am not so sure about that,” said Marchmont.  “It is all exceedingly mysterious.  Your suggestion is, of course, that the woman who came to New Inn in the cab was Mrs. Schallibaum!”

“Not at all,” replied Thorndyke.  “My suggestion is that the woman was Jeffrey Blackmore.”

There was deathly silence for a few moments.  We were all absolutely thunderstruck, and sat gaping at Thorndyke in speechless-astonishment.  Then—­Mr. Winwood fairly bounced out of his chair.

“But—­my—­good—­sir!” he screeched.  “Jeffrey Blackmore was with her at the time!”