Ronald Arbuthnott Knox, The viaduct murder (1926)
“ How could he tell that Brotherhood would get into the part of the train which hadn’t got a corridor, and that he would get into an empty carriage? What would he have been able to do, if Brotherhood had happened to come back as he always did—did, in fact, come back on Tuesday—in a crowded train like the 3.47? How could he be certain that nobody had seen Brotherhood get into the three o’clock? That nobody had noticed him at Weighford? Alternately, don’t you see, you make your man take the most superhumanly cunning precautions, and then trust to blind chance. ”
