Tom Anderson wrote:

I was at West Croydon station recently, and i noticed that the platform
layout is a bit funny. I can't find any good aerial photos of it, so i'll
draw a diagram (lines are lines, #s are platforms):

----------------\
############### +-\
X ######### \ \
---------------------X-+---- up Wallington
----------------------+------ down Wallington
###############

Any idea of there's a reason for this? Was there ever a third track there?
With the present platform layout, it would have to have been a bay
platform, but one which would have received trains from the Sutton
direction, which seems unlikely. Was it the case that the island platform
was narrower, and there were three through tracks? Was this line ever
four-track? Looking out of the train window further to the west, i thought
there probably would have been room for that - some of which is now taken
up by a tram track, but most of which is empty.

This was platform 2 (and bizarrely is still labelled as such by a Southern
sign that can't have gone up until nearly a decade later). It was the
terminal platform for the line from Wimbledon which now forms part of
Tramlink. It was lifted when the line was transferred over. Most of the gap
you noticed was the track for the line - Tramlink diverges early with the
flyover that was built.

As for receiving trains from Sutton, I seem to remember that there was a
points connection from the track that runs into platform 3, but I can't
recall it ever being used. In the bay's last years this would not have been
as unlikely as you suggest as there was a South West Trains shuttle service
from Epsom (only calling at Sutton in between, though later it took over the
Epsom to Guildford route off peak) that terminated at West Croydon. It used
platform 3 (the through London bound one) to terminate and set off again -
not the easiest of operations. I always wondered if platform 2 would be a
better choice, although I'm not sure if it would be long enough (it
certainly wasn't for 8 cars and the Wimbledon service was a 2 car unit).