He was the vanishing fellow I saw sitting on a chair in Baron Stott-Wartenheim's bathroom.

I told my friend that he was quite right.

The fellow was a secret agent to my certain knowledge.
Afterwards my friend took the trouble to ferret out the complete record of that man for me.

I thought I had better know all there was to know; but I don't suppose you want to hear his history now, sir ?" The Assistant Commissioner shook his supported head.

"The history of your relations with that useful personage is the only thing that matters just now," he said, closing slowly his weary, deep-set eyes, and then opening them swiftly with a greatly refreshed glance.
"There's nothing official about them," said the Chief Inspector bitterly.
"I went into his shop one evening, told him who I was, and reminded him of our first meeting.