Ian,
I work for NATS,I have not been asked to take part in any survey about stress,I haven't heard of any such survey,therefore it's not surprising that many of my colleagues are sceptical of your intentions.I'm sure they would be more than willing to give you their valid opinions when informed of all the facts.If you are not familiar with these forums,you might not understand some of the cynicism that is being returned in your direction.
If memory serves me correctly,prior to the 1987 WPP agreement,many ATCO's took part in a month long life style survey,which concluded that stress was not as prevalent in our industry as was thought.I look forward to seeing your report and HOW the data was compiled.