The doors at the end of the train carriage open and shut - electrical jitters. We are all travelling backwards, facing towards them, and the lighting and style are classic cinematic design: recessed stud lamps in the ceiling, for whatever reason dimmer as they approach the oval-panelled glass. There's a flicker of tension as everyone of my generation and clade thinks of the original Alien film. Then, of course, we relax.
But not entirely.