Mr Thant wrote:

The air-conditioned S stock will have doors that
automatically close if the train stands in a station too long, to keep
the cold air in, and it'll have working door open buttons to get them
open again.

Maybe they should have revolving doors on the trains.

I was once on a crush loaded tube train which pulled into a busy station,
but no-one wanted to board at our particular door, so the outside button was
not pushed. The people inside all had our backs crushed against the curved
door, and when we realised that the door wasn't opening, no-one could work
out where the door button was. Extra door buttons on the ceiling would solve
the problem, or sensors which automatically open [unlocked] doors if the
carriage is crowded.