CAP168 (Licensing of Aerodromes) states "The control of an AGL system from beyond the boundary of a licensed aerodrome will only be approved by the CAA for the sole use of the emergency services".
I think you are all looking too hard for a reason for this to be illegal. I see nothing in the rule quoted above which would prohibit the use of PCL. The only thing that it requires is that for a licenced aerodrome, that the control take place inside the boundary of the aerodrome.
Airports take up a reasonable amount of space. Surely with a GPS the pilot can position into the known overhead, and thereby be sure that they are within the boundary of the aerodrome when activating the lighting.
Once activated they can then go and position onto a downwind and complete the remainder of the circuit.
What they can't do is turn on the lighting from 5 miles away to help them find the airfield.
Yes it's a stupid rule, but I can't see how it would stop the legal use of PCL, so long as the pilot positions themselves into the overhead first
