Sometime around late eighties/early nineties the Army sent letters to a bunch of people who had failed flying grading (on the Chippie) saying that following a review, they had in fact been assessed as suitable for Pilot Training. It was a move purely driven by low student numbers and IIRC, just led to a higher failure rate on the subsequent course (anecdotal evidence, admittedly) and further validation of the value of flying grading as an assessment tool. Been a while since I've been back, but do the RAF/RN use grading or does UAS etc meet that need?