At that point, all the gnomes return to their secret chamber, and Stephen is free to take any gems that he chooses. Add them up yourself. He was right. Mr Wilder was found murdered in the waiting room at Bingchester Station. In each case the trains run every quarter of the hour, so the times of the trains before or after can be discovered by subtracting or adding 15 minutes.
All trains are precisely punctual.
Bingchester is also connected by roadway to the same towns. There are 5 persons suspected of the murder. It can be taken as certain that one of them is guilty. They each have a bicycle, and when cycling they move at a steady average speed of 15 mph. They can of course take their bicycles on the train, but no one uses anybody else's bicycle.