Near the Harry Potter thing in Kings Cross is a single escalator from
the northern tube ticket hall. I have only ever seen it running upwards,
and yet there is a sign over the top informing people of the
Underground, despite the fact that it is an up escalator. An endless
stream of disappointed people loiter around it. Presumably this was
supposed to be a down escalator, but it's been changed and no-one has
removed the sign?