Sure, there are a lot of very good ATCOs working non-State but if NATS has chopped someone, especially during initial training, there has to be a very good reason. The instructors working at the college have no hidden agenda; they want to produce good controllers. I would hate to think of someone spending a small fortune at one of the "private" schools and endinbg up in the same situation as when they left NATS.
Granted, there's no hidden agenda, that's out of the question. The work of the instructors is usually excellent.
However, after the failure, there seems to be contrasting standards regarding who gets a second shot, and who doesn't.
And most of the times, that second shot is what makes a lot of trainees successful, but some are never granted it !
Those tend to be management decisions, rather than instructors' ones.