And why would I know the number of kids in the year?! I probably should know more about the sets but like I said, I’m only really interested in my son. So when he comes home and says I’m in top at or second top set I have just left it at that.
@jossbee I do think the number is really relevant though.
If a DC is in set 3 (as yours was, you say) then how many sets is fairly key. Set 3 of 10 (10 maths sets in the school I worked in)? OK so fairly high. But set 3 of 3 (which I guess is possible in your DC's school) is a different story.
It's not a bad thing to be in a lower set if that is the best place, ability wise. The pace is slower and there may be LSA support. But the H/F tier issue is relevant, especially if, as I noted before, your DS is overall academic and likely to want to go on to study A levels and a degree – especially if maths or science may be in the mix.
As an aside, I realise that schools are different, but I find it surprising that there has been no indication in terms of targets, flight paths, expectations from the school – especially as GCSE choices will now have been made; you might expect some feedback there, for example whether a DC would be able to take on triple science, whether they should drop a GCSE, whether they were capable of taking MFL.
I agree OP that it’s worth following up on all of this with the school – ask for target grades so you can get a better sense of what your DS is likely to achieve, since you don't have much of a steer as yet. That will be useful in a year's time when you and he are looking at options post-16.