There are a couple of issues with the HST stock (and I presume the loco hauled rakes are the same) which allow the train to move with doors not secure. There is no door/brake interlock system, so the central door locking (CDL) system is completely self contained and has no ability to hold the brakes on or prevent the Driver from powering up. It is perfectly possible for an HST to move with the CDL released and all doors unlocked - indeed, incidents (thankfully rare) have occurred where a train has stopped, the Guard has unlocked the doors, and the train has moved again in the platform with pax attempting to board or alight. In addition, the CDL cannot identify a door which is open or 'on the catch'. The locking bolt will simply not drop into the door correctly, but the system has no way of detecting this and so the hazard lights are unaffected and will extinguish once the CDL is activated. This is why it is not uncommon for problems to occur with doors not being fully closed and secure. The only safety system is the eyes of the Guard and dispatchers, and it is unavoidable, bearing in mind the size of the train and the nature of a busy platform, that these things will happen every once in a while.
