"Peter Lawrence" wrote

Maybe there is now no safety objection to a signal in mid-platform
since slam doors have gone. If the signal is at danger the train will
stop there but the doors will not open; when it clears the train must
move on to the platform end for the station stop. This is inefficient
but not unsafe. Since the signal is for 'wrong line' movement, the
need to stop at it may never occur anyhow!

AIUI the rule book now requires a train not booked to stop at a platform,
but which is required to stop by a signal at the platform end, to stop
immediately before the platform until the signal clears. I recently
travelled out of Paddington on a Sunday, when the Up and Down Main were
closed for relaying. The Down Relief signal at Hayes was red to protect an
up HEx crossing from the Airport branch to the Up Relief, and we stopped
short of the platform until the signal cleared.

Peter