Answer me this. What is the difference between doing approach procedural and tower combined and approach radar with tower combined? Answer- one has been legal for many decades the other has not? Why not? What's the difference? IMHO approach procedural requires far more concentration than approach radar (I've done both for many years) so I would far rather (with appropriate restrictions/conditions) do a bit of approach radar in the tower than have to do full on procedural because of some outdated rule that nova body can quite remember why was introduced.
The reason this has come up now is because NATS dispensed with its ability to do approach procedural many years ago (rightly or wrongly) and so this is its only real option...and I'll lay money no non-NATS units get approval to do it.