It was hay fever, but I had thought of this and realised nothing ventured nothing gained. There's nothing stopping me trying and being told I am not eligible rather than not trying at all.
The Fleet Air Arm Officers Associations website says:
"By the end of the course it is anticipated that the students will have discovered whether they have an aptitude for flying or an interest in a career in aviation or in the Royal Navy. Many, of course, will fall away, but others will wish to pursue further the possibility of aviation as a career."
To me it sounds like this is run totally independent of AIB, and their side of things - although that may just be wishfull thinking. I believe this may give me a level playing field to others.