Indeed, ther are still a lot of really old & oddball systems about to various (or no) standards/specs.
e.g. last week visited a couple of 3/4 storey office buildings. One had a Gent 240V system of BGUs and 6" bells - & nothing else (the nearest thing to ctrl/indicator equipment was the 'ON/OFF' breaker switch for the circuit in the switchroom. The other a more "advanced" Gent system in as much as it worked on 24V with a battery bank and had a reset button in the lobby.
Although both were advised (again) for replacement, the 240V being the higher priority, like a lot of buildings, unless it becomes irrepairable or major refurbishment/alteration of the building occurs, it will still be in place for years to come.
So engineers & surveyors will be coming across oddities for a while yet
