Fabrifx,
I don't think anyone here would propose only recruiting candidates who have encyclopaedic knowldge of aviation. The concern here is that the training courses those candidates undertake once recruited are not long enough to prepare the trainees adequately for 'real life'. In fact, at a basic level, your post supports that argument: We no longer recruit exclusively those with background in, and knowledge of, aviation, and the 'real life' job is only getting busier and more complex, so surely that's an agrument for increasing the scope and length of training courses.
I think they are looking for people who have good logic thinking, good memory,fast and accurate workers, excellent decision-making people, and people able to concentrate under a lot of stress
Correct, and just because I'm feeling a bit mischievous, how does revising for arithmetic, spatial awareness tests and scenario questions before one's interview show any of the above traits? To be honest, I'd prefer it if NATS did not give out any examples or information regarding it's selection procedure. However, it is fairly obvious once you interview someone if they have read a bit of PPRuNe and think they can give the 'correct answer' to all the scenarios I throw at them! The words 'rope', 'hang', 'enough' and 'themselves' come to mind! 