In this case, the procedure was exactly the same. The signal knock, the demand for a number, and the reply “Correct.”

Two knocks followed in quick succession on the door below. The first man was quite unknown to Tommy, who put him down as a city clerk. A quiet, intelligent-looking man, rather shabbily dressed. The second was of the working classes, and his face was vaguely familiar to the young man.

Three minutes later came another, a man of commanding appearance, exquisitely dressed, and evidently well born. His face, again, was not unknown to the watcher, though he could not for the moment put a name to it.

After his arrival there was a long wait. In fact Tommy concluded that the gathering was now complete, and was just cautiously creeping out from his hiding-place, when another knock sent him scuttling back to cover.

This last-comer came up the stairs so quietly that he was almost abreast of Tommy before the young man had realized his presence.