There seems to have been a lot of potential for shenanigans.
I've been told they submitted a ranked list.
The school's results improved a lot between 2018 and 2019. 2020's are suspiciously identical.
Also there are lots of complications:
Pre-U Further Maths grades are similar to Pre-U Maths, for the country.
This is true every year, and makes no sense, because for A Level the A rates are MUCH higher, because only maths whizzes will take Further Maths, just as you'd expect higher A grades for say Music.
The result is that the school's grades for 2019 were overwhelmingly D1/D2 (A*/A) for Maths, but the much smaller and obviously more able group doing Further Maths got a lower % of D1/D2.
So in general if you get an A* in Maths A Level you'll probably get one in Further Maths A Level as well.
But that doesn't seem to be true for Pre-U.
Which is what it is and they signed up for that but they haven't set an exam to prove themselves and are materially disadvantaged relative to A Level students who will have been given higher grades overall.
Next thing that happened is that for some subjects (not Maths), the school did both A Level & Pre-U. This was true for Chemistry. DS' worst subject was predicted to be Chemistry. But because the A Level & Pre-U cohort are not considered as one, the context from last year is 'school of Chemistry geniuses', without realising that they've filtered out the A Level students and with them all the people who might get low grades (C/D/E equivalent).
So DS' predicted Chemistry (which he didn't need for this university place) is UPGRADED because he was in the 'elite of the elite' cohort by choosing Pre-U.
Meanwhile he's better at Physics but this is a unified cohort at his school. Here last year someone got a U. Bear in mind that across the whole school for a subject they wouldn't expect a U, or even the next two grades up from that (P2/P3), or maybe even a P1 either.
And because that happened last year, they have to give one out this year.
Even though that's probably a 1 in 1000 event that just happened to happen last year, and they don't have even 100 Physics students.
So I'm told some poor bugger got downgraded from an M3 to a U. Because if there was a U last year, gotta have one this year.
Anyway fortunately this wasn't DS, because he was ranked high enough.
So it looks like he was ranked by his school in the lower reaches for Further Maths. He was predicted a D2 (A*). But that doesn't matter. His rank says he gets an M1 (A/B), because that's what that rank would have got last year.
Now here's where the shenanigans come in. I have no idea if schools did this or not, but they would be dumb not to.
School has how ever many students it wants to get into University. Each has different requirements. So the Physics degree students might need an A* or A, so you'd rank them higher. Meanwhile let's say you have candidates for Oxford to study maths. You're going to rank them top for maths out of your cohort because that means they get their grades and get the place.
And then perhaps other students don't need such good grades for their unis. So why waste a high rank on them?
Of course it can backfire. And then you can blame the government/ofqual/China/whatever.