171 Bus Boy
Sleeping it off on the back seat of the 171 - hopefully. Who was to know whether this was just a casualty of too much good times, or something else? And what response would an offer of help or concern get? According to the general wisdom, anyone can be an enemy. And young people carry knives. So don't get involved. If someone wants to die on the back seat of a bus, what business is it of ours?
So the entire bus from Peckham to Catford simply turned away and hoped for the best.
Assuming again that this was innocent enough, and ignoring any larger condemnations of society for the time being, the more mundane fact is that this spectacle is only possible on the unsocial, greasy ghetto of the top deck of one of Batty Boris Johnson's beloved routemasters.
Downstairs, or on a Bendy Bus, instant peer pressure, facial contact and a diverse passenger list creates a far more social environment, and people tend not to disgrace themselves.
Shame Boris can't learn the same lesson somewhere.