The Vanished Messenger by Edward Phillips Oppenheim

Excerpt:
There were very few people upon Platform Number Twenty-one of Liverpool Street Station at a quarter to nine on the evening of April 2—possibly because the platform in question is one of the most remote and least used in the great terminus. The station-master, however, was there himself, with an inspector in attendance. A dark, thick-set man, wearing a long travelling ulster and a Homburg hat, and carrying in his hand a brown leather dressing-case, across which was painted in black letters the name MR. JOHN P. DUNSTER, was standing a few yards away, smoking a long cigar, and, to all appearance absorbed in studying the advertisements which decorated the grimy wall on the other side of the single track.