Its not aptitude that has the greatest bearing on first time passes but ATTITUDE. Having been an instructor at the big school somewhere in oxfordshire in the last few years I have come across students from all sorts of backgrounds-the vast majority have not had a degree.
Their success in the exams tends to be in direct proportion to the effort they put in,followed by good teaching and finally FEEDBACK.
Of course some really do not have the apptitude but with a lot of hard work and perseverence they have finally got through, and from personal experience it was worth the effort.
My own experiences:
CPL's some ten years ago-3 times to get the pass,my attitude was at fault.
ATPL's some 3 years ago-first time pass in all subjects,thankyou ATA (pete lines and quinlin),much improved attitude but I wouldnt say my aptitude was any different.