Climebear,
Yes, I agree that it would be very expensive, but how many aircrew are likely to PVR over the next year? How much flying pay does each stand to loose? If they worked together, maybe they could challenge.
You say that you do not believe that there is any specific legislation which applies, but what about the one we are discussing, the "Council Directive 2000/78/EC of 27 November 2000 establishing a general framework for equal treatment in employment and occupation". Although it may have been at the forefront of their minds, I don't think this directive was written solely to counter sex discrimination. Discrimination based on religion or belief is also covered and you could, hypothetically, argue that you now wished to PVR for those reasons. Would a pay cut under those circumstances be legal under EU law?