MikeS
I did the Navy Flying Aptitude test at Biggin Hill in '91 and was told that to pass for RAF you need to be in the top 80 percentile but for Navy you need to be in the top 90 percentile. If you know what a standard deviation graph looks like then this is the thin bit at the bottom RHS.
It makes sense if you think about the following scenario: returning back to your carrier at night, low on fuel, sub in the area so the carrier is lights and radio silent, and has moved from expected location, and there's a big sea...
I'm not saying the Navy pilots are better, only that the minimun aptitude requirements are a bit higher.
I passed both Pilot and Observer and went on to get shortlisted, but was too old to apply for the RAF!
Good Luck.