When I started on the railway in 1973, we were 'instructed' when on or about the line to observe any passing train to see if it was 'carrying' a tail lamp (couldn't always tell if it was 'lit'). If not, then you had to contact the nearest signal box and advise the signalman. I personally did this for the next 46 years of my railway career. I only ever observed 'no tail lamp' on two occasions in all that time, although on one of the occasions, as I had an NRN mobile radio with me, I contacted Route Control instead - it was quicker!