ATC expert (sic).
Of course the greatest risk is in the stack. SRG reccomended display of levels many moons ago (over ten years) and NATS are "still looking into it". EGAA see messages passim. Not to mention SMR.
SRG is not going to be given powers that enable it to force a private NATS to buy expensive new equipment. It would be commercial suicide for a plc to buy into a company where they have no control on future expenditure and are unable to increase costs at will.