What we don’t see, of course, is what goes into the reference. I was reading somewhere on the Cambridge website that they ask teachers not just to use the word “outstanding” (as they all do this apparently). Instead they want actual evidence - eg. “top performer in a cohort of 20;” or, “scored 90% in a recent exam, which is a high A*. In other words, teachers have to provide evidence for their predictions and where they can (ie recent exams) , it seems this will give the grades more weight.
I think predicted grades possibly matter more for subjects where there is no admissions test, such as the subject DS is going for. He does however, need to submit two essays (but this is not the case for most colleges for this subject, so it does vary and I do wonder how they standardise it).
As for the Tompkins table, everyone says it’s a load of nonsense and it probably is, but still, if you look at the course requirements per subject for each college, some do require slightly higher in the IB - is not sure if this translates into higher admissions standards? I guess colleges at the top of the table probably want to stay there? But ultimately, I would think it depends on numbers of applicants per place for a given subject in a particular college, rather than the college admissions ratios overall.
Then on Unifrog, it states that some colleges have a more favourable admissions rate for independent school applicants than others - eg 60% at Homerton apparently (!), but only 20-30% in other colleges. I don’ t know how much to read into this either?