Having been a union rep in two different unions (Unison & Amicus/MSF) during my sojourn from NATS, I know only too well that it's a thankless task. But as I always said to the guys I represented, 'you need to tell me what you want before I go banging on the management's door. No good bitching that what we ended up with wasn't what you wanted.'
At my last unit, they had a habit of promoting the union reps to positions where they had to give the union job up. Still, I'm sure NATS has figured out that having a poacher wearing the gamekeeper's jacket is a handy thing for them.