@chopc, I guess the majority probably not from disadvantaged backgrounds. But I do know a number of people who are / were on full bursaries in independent schools that are from disadvantaged backgrounds. Doing or that have done IB in the past. I guess going to those schools helps bridge some ( but not all), of the disadvantages.
The not knowing is frustrating, the schools are frustrated too. And the predicted grades sent to IB, won’t necessarily match the ones sent to UCAS
Those will be determined by how they do in their mocks and a few other things. They’ve done a fair bit of course work, to be fair. But it’s just all up in the air at present