When announcing that a train is too full and for some passengers to leave a Guard should be polite and take into consideration that people who pay £4000 pa for a ticket do not want to be home late or crammed up worse than cattle. An simple announcement like this
"unfortunately due to this train being severely overcrowded we cannot leave the platform until some of you get off the train, (Rail company) apologise for the inconvenience and delay to your onward journey this may cause you"
is much better than
"We are not moving until some of you get of the train "