From my experience:
'Good evening everyone. I have some important info about your onward journey today. Unfortunately, the signaler has just told me the line ahead is blocked, due to trespassers. We'll remain here at the station for the time being. I don't have a time yet for our departure, but I'll keep you informed.'
*2 minutes later*
'The signaler has just been in touch and has informed me that the line ahead is blocked due to trespassers and he is awaiting the arrival of Transport Police. As a result, we will remain here in the platform awaiting further instructions. If you wish to stretch your legs on the platform, you can do and I will let you know when we will be departing. As I say, I have no time for our onward journey, but do remain with us and we will get you to your destination.'
*cue exodus of passengers to taxi rank and me becoming all sorts of wonderful insults. Some passengers step out onto the platform*
*further three minutes*
'Well folks, signaler has just let me know we can go forward, so we'll be leaving shortly.'
*steps out, blows whistle. Folks on platform stub out fags, jump back on. Wait 15secs. No one else. Close doors, safety check, buzz buzz. Away we go. Folks at taxi rank, outside station, wave fists and gesticulate*
Next day... please explain why I left passengers behind at station...
Explanation given, no problems, carry on.