"Tube Etiquette No. 9: Litter and Baggage" London Local Custom Tip by Cham

Please don't litter in the underground not only does it leave everything looking disgusting but there's a more official reason as well.

You'll notice in no tube or train station there is waste disposal unit (rubbish bin). This is because of the IRA bomb threats during the 70's - 90's and this is also the reason why littering is a bad idea. The number of stations that get evacuated for bomb scares isn't as bad as it used to be but it does happen. this causes delays on any of the lines running through that station and generally takes a long time to clear the backlog of people, and most of the scares turn out to be a packet of sandwiches that someone has left behind.