Sigmets
Not hugely relevant to the exact topic but:
Over 20 years ago at LATCC, West Drayton (RIP) management perceived a requirement to ensure that controllers transmitted pertinent SIGMETs to pilots, following an incident abroad where forecast turbulence was not advised to an aircraft and it got caught in horrible chop, which resulted in severe passenger injury. M'learned friends got involved and NATS higher management thought they might find themselves before the beak being sued if something akin happened over the UK.
Those of you old enough and still with a memory might recall the SIGMET strips which arrived on the boards on which the CSC had to scrawl a sigmet number in chinagraph alerting SCs to look at the CCTV info and tell all the pilots.
Of course it fell by the wayside as it was impractical to filter the information and target it to relevant aircraft especially on highly RT loaded sectors. The information flow was flawed and could not be relied upon too.
The basic MATS 1 requirement for controllers to provide known essential flight safety information is still there, but practically speaking how far can you go with this as an individual controller or as a unit/organisation? I guess NATS could still be found wanting in this regard, given a sharp enough legal eagle.
An interesting topic, which will probably never be satisfactorily resolved unless every single aircraft can get real time relevant info uploaded, then we can blame the drivers.