The Wings of Victory by Fred M. White

As Mary Dorn spoke, a scrap of paper fluttered from her fingers. It was apparently part of a charred letter or envelope, and had no doubt been there, protected from the rain by a fragment of charred wood, all these years. Dorn glanced at it carelessly enough, much as one regards some gaudy flowering weed which a child has gathered from a neighbouring hedgeside under the impression that she has found a treasure. It was only a tiny scrap of paper with the ink faded, a scrap of paper that had been evidently torn from an envelope. There were only two words "street" and "London, E.C."

"Ah, you are in luck this morning, my dear," Dorn said. "And now having done so much, don't you think it about time that you went in and looked after the lunch? Sylvia, I want you for a moment or two."