Just to be clear, I am not saying there is any safety case re: air carrier airports (which I was thinking of as say 50000+ transport category movements), just that with the very strong resistance from our continental airline cousins, it is a possible way the 'permitted airspace' would be defined. With the demonstrated safety record of the IMCr operating into all Class Ds it is difficult to see any logic reason why it isn't permitted in Class A as well, but no one is arguing for that change.
Re homeguard on LFAT etc having controlled airspace - that's the way it works everywhere else in the world, IFR airports are in controlled airspace (but not operated like the UK's where Class D sometimes feels like Class B!). On the plus side, if the French followed UK rules then all of their airways would be Class A, they seem to have a much more relaxed view of their enroute airspace than the UK.