Fair enough, if you look on streetview you will see it goes all the way to the buffers. I'm sure I read somewhere (a long time ago) that the preservation society deliberately extended it so that it was long enough for all their carriages to be platformed. I remember being puzzled as to why that was a good idea at the time, and it still sounds a bit oddI couldn't tell how much of the covered section was part of the platform, which probably explains the difference.