Stage 3
Pete - the scary thing is I thought I had done really well, all three interviewers were completely pocker faced though! I don't think my advice would be much good to you as I did not get through, however questions tended to cover your personality, ie strengths and weaknesses, decision making abilities, believe it or not there was barely any technical content, which was not what I was expecting at all. Make sure you get as many visits to a unit in as possible, one visit in my opinion isn't enough. Make sure you have a thorough understanding of where you want to go in NATS and why. Oh and make sure you know all about NATS the company, ie PPP, services provided etc.
hope this helps, hope you have better luck than I did...Good Luck!
Let me know how you get on and if you make it through maybe you can give me some hints and tips!