martin writes:

travelling on a 37 this morning, one of their new stock
I was rather surprised to be told by the lady who tells
us everything on buses, just as the door closed:
"please hold on the bus is about to move" I thought most
bus passengers understood that or is it not obvious enough
since we havent quite perfected teleportation yet.

It is not really that new. "Hold on tight"
dingding was1[1] a standard announcement by conductors.

[1] Along with "Any more fares, please"