TCR, Whilst it may seem harsh to have your fate decided so cruelly you have to bear in mind the enormity of the task were we to interview all candidates. NATS received over 30000 applications last year of which little over 2000 would have been interviewed for an eventual college intake of 100 or so. The interview panel is a small band of merry men (and women) who do the interviews as an addition to their regular job. We simply don't have the resources to see everybody and the recruitment process whilst far from perfect has been refined and redesigned over the years to try and yield the best results.
The bottom line is that you have to have certain qualities and attributes to be an ATCO (described to me years ago at my interview as "having an unusual set of tools in your box!") which can be identified by the online questionnaire.
As sad as it is for somebody who is desperate to do the job it could just be that you don't have those tools.
Don't let me put you off applying again as it is true that many who get through do not do so at the first or even second attempt. Just trust that NATS does have some idea of the people its looking for and it could just be that it aint you.
Good luck!!!!!!