noblegiraffe I don't really buy the idea that the JMC is inappropriate outside top sets/selective intake. Surely almost any y7/y8 can do some of the questions in the JMC, and can attempt enough to occupy themselves for an hour trying? Am I being very naive? I could see excluding a bottom set of children who really struggled with maths - but which of the first 10 questions of the 2016 paper do you think an average y7 could not even attempt, and why?
DS's non-selective [yes, except by ability to pay fees] independent school enters the entire cohort I'm pretty sure, as well as selected young ones; they also all do the PMC earlier on (so then the JMC is a natural progression anyway). As far as I know they don't teach specifically for it, but they do seem to make problem-solving a big part of what they do on a day-to-day basis.
Agree about it seeming to be mostly y8s who get through but not by a huge margin. Don't know about the independent/state split. What I am very struck by is the preponderance of independent schools in the UK national finals of the TMC each year, at least in my area (outside my area I can't always tell by the name of the school, and haven't bothered to analyse the list). In our area, all the finalist schools are independent, even though several of them are not academically selective, and regularly beat state schools with excellent reputations that, because of size, have five to ten times as many pupils from whom to pick the team. Why? It's not that the independent schools coach for this; it's not that the questions rely on material beyond the syllabus the state schools are doing; it's not that the state schools don't enter. I am genuinely perplexed. I mean, pleased that my kid's school does well, but something is weird.