The rumour mill seems to start churning about the same time every year with stories about the ultra high scores required to pass the KE Foundation exams. These are inflated rumours - I don't know why some parents start them.
We have had a number of dicussions on this and I did obtain the actual scores from the KE Foundation (under a FOI request) for the 2005 exam and the scores were nothing like that. In fact the KE Tests are quite tough (mainly through time pressure) that the actual scores are very much lower than comparable NFER type 11+ exams throughout the rest of the country.
Take a look at the following previous thread for more information:-
If you look at the statistics for KE Grammar school entry you will see that about 1 in 6 get through; so it tough to get in, but no more so than other LEA 11+ exams. The 100% is definitely wrong.