Sure common sense would be to approach a member of staff, explain you thought you where on the right train, and you've realized your on the wrong one, rather than pulling the emergency handle and hoping to run away.
Maybe in the general case, but not on a driver only operated 387s. But at the same time it should on modern stock be possible to communicate with the driver without stopping the train.
Paul
As I believe is the case with the Class 180, and should be with the
IET▸ (however, seeing a video on youtube makes me wonder). Is there a system where above a certain speed, the alarm activation required the person to speak to the driver once he has pulled to a stop in a location of his discretion, and at slow speeds, if the alarm is pulled the train comes to a complete stop(i.e leaving a station)