My child is at St Peter's Primary, Harborne, (which is a 2-form entry school with up to 60 pupils per year group) and tells me that about a third of the class took the KE exam. If this is repeated in the other class then approx 20 from St Peter's took exam.
Obviously nowhere near that number got places last year, but I don't know how many took exam.
gives destinations of last year's leavers. I would assume that the children who have gone to independent schools most probably were among those who took KE exam.