387's on Thameslink only had first class at one end not both. Thameslink is unusual that it turns units in service so having first class at either end make sense (for the 8 cars). Logic then dictates that carries over the the 12 car as well.
Whichever way anyone tries to spin it, the positioning on the GN 387s just doesn't make any sense.
Issues with placing the first class where it is:
1) Guarantees people will be walking through it, either when joining the train, or to access a toilet.
2) By placing it at one end of the train it opens up the possibility of some trains facing the other way, which is exactly what has happened with the GN 387s.
3) First class is positioned directly above a motor bogie which gives a poor ride - especially on 387s which don't ride well. One wouldn't mind if there was a trade-off benefit, for example the location offering privacy like on the 365s, but what they've done on the 387s doesn't offer this.
4) Biggest problem of all: technically the vestibule in the first class area on the 387s is unavailable for standard-class passengers to stand in. If standard class passengers do stand here, legitimately or not, this will disturb first class passengers. On a train where seating *and* standing capacity is already compromised compared to what they are replacing, this is a major problem.
5) We now have a situation where one doorway arriving at busy platforms is unavailable to standard class passengers trying to find a seat. Worse, it's unpredictable at the moment because the trains face different ways. Misery for standard-class passengers who if they are unlucky enough to find the relevant door stops where they are standing then they are last in the queue for seats (despite potentially having arrived early), and misery for first-class passengers who get disturbed at every station stop.
6) The isolated standard-class section beyond the first-class is missed by many. This increases crowding on the rest of the train, already compromised because the 387s has less seating and standing capacity compared to what it is replacing.
GTR need to move the first-class to be located at both ends. Someone will confirm, but I believe this would retain the same number of seats, but would improve the situation for everyone, and release one vestibule on the train for standard class passengers to use, which otherwise is currently wasted.