“Thank you, Dr. Priestley, you are very kind,” replied Mr. Ludgrove, in his deep and pleasant voice. The Professor glanced at him in astonishment. Neither the voice nor the intonation were such as he would have expected of a herbalist in Praed Street.

“It is a beautiful evening,” continued Mr. Ludgrove. “Shall we walk to my house, or would you prefer to call a taxi? I know that the vicinity of Praed Street has a bad reputation as a result of these deaths, but although, as you probably know, I received a numbered counter some weeks ago, I have so far come to no harm. You need have no apprehensions once we reach my house. The police still display considerable concern for my safety.”