I am going to have one last go at explaining and then I promise I will give up and leave it.
The point about feeder preps is not just that they know how to prepare boys for these unbelievably tough exams, but they also know, from long experience, whether it is in a child’s best interests to sit for them. It is about more than just a few good CAT scores in year 6 - it’s to do with maturity, potential, work ethic, attitude to extreme difficulty, and also what the goal really is. Is it to be in with a chance of winning a KS or Election, or is it because the boy will really benefit from the preparation process? (A responsible prep school - and the senior schools in question - would say that the latter is more important than the former.)
As you can see from other threads, this is not a straightforward decision, even for the brightest of boys. It needs to be a three way conversation between the school, parents and boy himself, because it requires enormous commitment from all three parties and if any of them aren’t fully bought in, it will be a very difficult and probably counter productive time ahead. Many parents decide that, while the idea is very flattering, it is not in their son’s best interest, and there will be ample time once he is at Eton or Winchester to dazzle academically.
What is worrying about what you have described is that your son’s current prep can’t and won’t help your son prepare, knows nothing about the process, AND, worst of all, is in no position to give you informed advice as to whether this path is genuinely in his best interests.
You say changing prep is not an option but if your son is ultra, ultra talented and obviously capable of winning KS with no school support, then any KS feeder prep in the land would welcome him in Y7, possibly even with a scholarship or bursary. In some cases, senior schools will even subsidise the last two years of prep school for outstanding candidates. Worse case scenario, you will gain useful information from having those conversations, from people who really know what they are doing.
If you are unwilling to countenance that route, then the only viable alternative is tutoring, from a specialist company with a track record in preparing successful KS candidates. But there are disadvantages to this. First, it will cost you many thousands of pounds, on top of whatever school fees you are paying. Secondly, financial incentives inevitably impact what the tutors say and do. There are some tutors who take on and/or retain long shot students with desperate parents because money talks. Thirdly, all this intensive tutoring will be happening on top of school hours and the CE curriculum they teach, so you need to think about the impact on your son of trying to do both. For candidates at KS feeder preps, the preparation is gruelling enough as it is, but you will be expecting your son to do all this AND his normal school commitments.
I don’t need another polite response saying thanks but can anyone recommend the right prep books from WH Smith. Instead please ask yourself whether you have enough information yet to be certain that the path you are choosing is in your son’s best interests. That’s all. Over and out.