As the kids are not allowed to write on the papers there has been suggestion that they are re-cycled in some way. Also, apparently, there are occasionally question types on there not covered by practice VR papers (my DS said there was a type he hadn't encountered before a few years ago). If we were privvy to all the 'tricks' the examiners had up their sleeves then what fun would that be??
The practice papers are examplars of questions which may possibly appear on the actual test. I think we have all wished to see exactly what is on there but alas...no chance
Even should one go to appeal (and request to see the child's test) you do not get to see the question paper, only the child's answer sheet.