Wot No Coverage?
It seems that London Underground has put the word out round its managers that uncovered duties are to be left uncovered unless it is really really definitely crucial to the station's safety.
The thing is, management's definition of safety is rather diffferent from owrkers' definition of safety. And progressive staffing cuts over the years have meant that pretty much every duty on the job is crucial to the station's safety. Any that were not were got rid of years ago!