Emergency medical care on the train

The worst thing you can do is to pull the emergency stop handle, which will halt the train more or less straight away, possibly in the middle of a rural area a long way away from any roads. Communicate with the train manager who can assess the situation and if need be, can phone ahead and get paramedics or a doctor to meet the train at the next station, whether or not the train is scheduled to stop there.

I don't think the emergency stop handle stops the train...  It alerts the driver who then will, depending on the train model, converse with the carriage that pulled the alarm via the intercom, or stop the train safely and then locate the source.

A lot of trains within the M25 don't have conductors/guards/managers.  All modern cost reductions.

He will stop the train and then locate the source.  In which case, I will agree that stopping the train is not the best idea.

Most trains actually do have conductors / guards now, as they have been re-introduced as a fare evasion prevention measure.

(Gosh, kitson, I feel like I have been disagreeing with everything you say since you came back, I'm so sorry!!!)

Vicky

I will have a look for the red button next time I'm on the train.  Don't worry, I won't use it unless it's a real emergency.

On rolling stock built in the 1970s and 80s, pulling the red handle opens an valve in the brake system air supply and trips an emergency brake application. On later stock, it alerts the driver, who will stop the train at once, but not in cert places, e.g. a tunnel or on a high viaduct.

I will have a look for the red button next time I'm on the train.  Don't worry, I won't use it unless it's a real emergency.

The guard/conductor will almost always make an announcement saying where he's located on the train if you need help.  Or you'll see him walk through and know what direction he's gone in. 
If it's a long journey it would be unusual for there not to be someone on board.