To fly BHX-WAT, one has to make a booking either with a travel agent or directly with Flybe. As part of the reservatiin process, Flybe will capture the address of the cardholder for all direct bookings. A half decent database or marketing analyst should be able to analyse this address or post code data to see not just where UK originating passengers live, but also where the frequent flyers or high fare spenders on a route live.
This is of course valuable commercial info and not likely to go anywhere near the public domain. A small summary of selected snippets might be passed to Waterford's commercial team.
Either you have priviliged access to Flybe's commercial info in which case your job requires you keep your mouth shut in public, or the hard data proof just won't be available to you.