What I keep looking for is a parent whose child passed the exams last year posting to say their child averaged 80-90% on NFER practice papers.
I think a lot of it depends on which areas and which schools are concerned.
In the very highly competitive areas or schools(10 or more children trying for one place), the bar is raised.
Whereas in areas where there are places for all children who passed their exams, the scores can indeed be lower.
In Herts, the competition is particularly stiff especially with regard to capacity of the schools or different selection criteria(music or technological aptitude).