Originally Posted by
Mariner9
.... noting en route that half the escalators were already marked off unservicable ...
This is a Heathrow speciality (and the walkways as well).
I recently was on the walkway from the Central Underground station to T1 in the early morning. Ahead, an overloaded baggage trolley jammed at the end of the walkway, those following it started to trip over it, then it overturned. I was close to the emergency stop and pressed it (just as well).
Coming home in the evening I noticed it was still stopped, and a distinctive paint mark I had noticed in the morning showed it was still stopped exactly where it had stopped it. In 8 hours and tens of thousands of passengers nobody had bothered to come round, see the stoppage, and restart it.