In message , at 12:12:36 on Sun, 3
Aug 2008, Tim Ward remarked:
In slam door days there were three options:

4 - everybody just got onto the right carriage in the first place, as per
the notices and announcements at the point of embarkation - "front two
coaches for x" etc.

That's usually because the trains split, rather than a short platform.
For some reason this is regarded as less passenger-unfriendly than only
opening half the doors, presumably because at the station where the
train splits there's the ability to change units if it turns out you are
the wrong one.

Perhaps one of the options for the Cambridge trains is to run fast to
Letchworth then split into 8 & 4 car units. One running fast to
Cambridge and the other becoming an all station stopper.

--
Roland Perry