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,...