I won't go into too much detail, as some legal action might still be pending, but yes, it does cause us a problem with interference. Not only on the VHF voice frequencies, either, recently we had a spate of pirate radio interference with ILS signals.
On the other matter, 'internal' NATS applicants (ATSAs etc) have sometimes been handled differently, and 'sponsored' by their own unit (as many non-NATS units do) after having a gained a few years experience. Some of those might have been unsuccessful applicants.