This is very tenous and several parties removed from the source - however, I understand someone recently at OAT got 23% when he was expected to get in the 90's. OAT requested some kind of re-mark type procedure and he was then given 100% by the CAA.
We were told this while being instructed on the importance of correctly filling in the answer sheet (which this chap had not) but it could well have been a story to make sure we did it properly (although it came across as fairly genuine and not from the sort of person who would normally make something up).