Sounding the whistle

The train with the whistle sounding was in the tunnel behind the one held at the platform. The reason for the platform hold was that a passenger alarm was set off on the train ahead. Nothing to do with signal failures or passing limits of movement.

on a conventionally signalled line after five minutes if the train op is unable to make contact and get information about the delay he/she should apply the rule, providing the signal is an auto, trip past it and continue on to the next signal or train ahead. I have no idea about ato lines.

I too am guessing as I don't know the exact problem, but I imagine if it was expected to last a while the train behind would normally be moved forward "under rule" as far as possible to the next station to at least give the passengers a chance to get off. How they'd get them off with platform doors I'm not sure though; via the driver's cabs of connected trains? I believe "applying the rule" is similar on ATO lines - rather than signals they would, as domh245 postulated, be given authority up to a certain point, in this case the train ahead. As the original poster did not mention passengers being detrained I guess the original problem was sorted and both trains would continue as normal, albeit the second one still being "under rule."

"Applying the rule" (or "procedure") is a railway term for passing a signal at danger, part of which entails blowing the whistle every 60 seconds. I know you said there was no signal problem here, but on a conventionally signalled line at least a train can be authorised past a signal to bring it closer to the platform / train ahead during a long term shutdown, which sometimes happens if someone is taken ill, the usual reason for a passenger alarm. I believe on ATO railways it is similar, just that rather than there being a physical signal the train is authorised to go beyond its current "limit of movement;" this would be done at slow speed, indeed I think it would be physically impossible to travel at anything greater than slow speed in those circumstances.

From your description it COULD have been this was the case; the train stuck in the section behind your train may have been stopped by the system (on ATO lines they can get pretty close) and then given authority to move up closer, necessitating the use of the whistle in so doing, the slow speed meaning you may not have been aware it was actually moving. It could simply also have been that the driver of the train behind was unable to get information from the line controller and was just trying to attract attention to try to find out what was happening, although again with platform doors how any member of staff on the station would relay that information I'm not sure! ....Or maybe the driver was just getting impatient!!!

Rule 55 in the black-and-white rule book! "Passing signals at Danger". Can't remember what it is in the new rule book which came into force in 1970 even though I had to learn it. As to the latest rules, not a clue, but there's still a bit on passing signals at danger.