When I had to report a crash on the opposite carriageway of the M1 late at night, I used the "M1 A 123.4" emergency location sign, but said "Accident is on the opposite B carriageway, roughly opposite this sign". The operator wanted to know the f-ing postcode! When I couldn't give one (random locations on motorways don't have postcodes) she asked what junction or service station I had last passed. I'd no idea: I was somewhere in the middle of my journey, a long way from the junctions I'd joined at and was planning to leave it, so my location was "somewhere in between". I could give a very rough idea, but no more than that.
I was rather horrified that the police 999 operator couldn't handle the information on the "M1 A 123.4" sign, because they are there for this very purpose: giving a location in the event of an emergency. When I got home I emailed the police force for that area to report the problem because there was clearly a training issue. I had a reply saying that they'd found the recording of my call and agreed that I had been very precise and very unambiguous and had given all the information that the operator *should* have needed. The control room had identified that more training was needed...
On a previous occasion I had to give my postcode, and the operator had difficulty understanding the radio phonetic alphabet, which was an even worse deficiency of training. She asked me to give the letters their normal names, and then we had the expected "is that P or B" scenario that the phonetic alphabet is designed to avoid.