Thanks everyone, I knew I'd find people here who'd understand :-)
Yes, it will be a lot easier once they've met him; this is just the preliminary enquiry stage. We do need to take some steps because this year he needs to be registered with the schools we're considering (in most cases). This involves us paying a fee (a small one, relative to eventual tuition fees, but enough to deter us from simply registering him for every school we're even vaguely considering - which of course is the idea, on their side). Then in two or three years they evaluate the children registered with them, and make provisional offers of places. Children with provisional offers still have to pass an exam at 13, but the intention is that if you have a provisional offer you are strongly expected to pass.
I could have omitted any mention of what DS is like at this stage, but it's interesting to drop something in, so as to see how they do react. For one thing, we feel increasingly positive about the one school that did not react with a "we don't believe in acceleration" speech, but rather with "hmm... we haven't anyone quite like your DS sounds, but...".
No sign of the email from the HoM yet; maybe this is positive as indicating that someone realises it needs to be carefully worded.
DeeDee, I love the image of the "math deprivation chamber"!
