First they can't keep the carriages together, now they can't keep a panel up. Is it normal for something like this to happen and for the train to stay in service?
It's rare but I have known panels to come off on several separate classes of Southern traction. Probably a particularly pessimistic absolute maximum of once every couple of months of riding trains intensively. Interestingly I've only ever known it in the
cabs of 455s, where passengers have no reason to go. And yes, before anyone asks, I have reported all such incidents properly...
A lot of ceiling panels on Southern 455s are secured using recessed but fairly rudimentary fixings (I won't specify which, for basic security reasons, but many are readily observable, of course) and it may not easily be possible to see precisely how secure or fatigued some types are at a glance, or during train prep or maintenance which does not involve opening them. I'm not excusing this incident but this may explain things in part. At this time I have no idea what the investigation has uncovered or what it may continue to find.
However, whilst injury is quite possible and even likely in such an incident, this is not quite the same breed as an accidental division in service.
Lastly, if this happened in service, the relevant coaches (and any adjoining ones if required by fire regs) should be locked OOU. This is quite quick and easy on a 455 though due to the absence of Door Out of Order lights, it can cause confusion and extended dwells at stations.
Very lucky no one was hurt. As for no first aider - only if there was a job which can do first aid...
That wouldn't be a conductor, if that's what you're suggesting. Southern conductors have not had first aid competencies for quite some time.
However, that said, a conductor would be able to organise a response whilst still on the move, and request the necessary assistance as quickly as possible in a professional manner.