I also don't get why it's OK to have questions that are not taught in the State School (or rather, that level isn't taught - level 6 right?). That seems like a structural disadvantage for state school pupils to me.
It's not just the level! Until last year, selection for Gloucestershire's GS was solely on VR, which is not covered in state primaries at all, whereas I believe all the local indy primaries do it. They know that a significant part of their market is parents who hope that an indy primary education will get their child into a GS and be cheaper than paying for indy secondary.
I have said before, given that I would prefer to see the back of selective education as a first choice, if we have to have it, it would be great to throw some really off the wall things at these kids. Maybe map reading, assembling a broken bicycle, following a complex recipe or using birdsong recordings and habitat information to identify some birds, which really couldn't be tutored for. Everyone would be at the same disadvantage and it would allow children with a bit of something about them to shine. They could be told they were going for a bit of a fun day out and that it wasn't a test at all.
What fun! Indies could do this if they wanted to. State schools, however, are covered by regulations that say they have to be able to prove that their testing system is completely objective, and sadly, I'm not sure that you could assess the recipe or bicycle without being at least a bit subjective about it. (Actually I suspect that indies would find it required too much teacher time (both preparing and supervising/assessing) and wouldn't do it either.)