Indeed, those trains were very common when I worked for B.R. back in the early 1970's. We called them the "slam door" stock. Similar coaches had less doors, and the interior compartments were removed, but one could still lower windows and the doors "slammed" to close. One feature of the exterior door handles was that if a door was open, the handles stood verticaly, and closed they were horizontal. If not quite closed correctly, they stayed at 45 degrees, so station staff looked at them before giving the "right away" signal.Caravanman, that video has one of my all-time favorite coaches (I think) arriving on Platform 15 at the beginning. Each compartment has its own door to the platform which is very cool!