The CAA said (above)
The published rules specifically forbid the lights of a licensed field from being turned on by someone outside the airport boundary. PCL does just such a thing - therefore you can not have PCL for general use.'
The actual rule (CAP 168 Chap 6) is;
11.1.3 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. Where this type of control is desired, an operational requirement proposed by the aerodrome authority and supported by the emergency services involved should be submitted in the first instance to the CAA.
The ANO is silent on the matter. The key word is licensed.
So the argument hinges on the CAA's assertion (above) that a licensed airfield remains licensed outside its opening hours. As sometimes happens, an outwardly quite true statement conceals the real truth which is that although the licence is not withdrawn during closed hours, its
conditions only apply within opening hours.
If the CAA were right, there would be the absurd situation that an unmanned unlicensed airfield, of which they are many, could safely provide PCL for night use, while its neighbour, licensed during daylight opening hours but not when closed and unmanned at night, may not do so.