Steve Fitzgerald wrote:

No, it latches down and has to be physically reset with a J door key.

Good. On the occasion I used one for genuine reason[1], I don't think
it would have been obvious via CCTV that there was a justifiable reason
for it, as the train was very crowded.

Actually, on that occasion, I'd say I was disappointed in how the staff
initially handled it. I had expected that (as it was D-stock which
doesn't have a means of speaking to the driver) he'd immediately walk
up the train and see what was up. It took a few minutes before what
appeared to be a member of platform staff noticed me waving frantically
out of the door at them, and the priority seemed to be towards making
an announcement that was in a "we will be delayed because some twit has
pulled the cord maliciously/by accident" type of tone. Is there
perhaps a policy of the driver not attending a passcom incident alone
in case he is attacked?

[1] Very unwell-looking and almost unconscious (or possibly drunk, I
couldn't tell, he didn't particularly smell of it though) man with
panicking young child. I pulled it in the station to get staff
attention to have both of them taken off and sorted out, it seemed the
most appropriate thing to do rather than lead the child off myself as a
"stranger" given how scared he looked. Once dealt with, the passcom
was reset and off we went, with no suggestion afterwards that it was
the wrong thing to do.

Neil