Mocks can only be used if the school is able to validate they were sat under actual exam conditions. Thankfully all ours were in exact same set up as real exams with external invigilators.
However, different departments took different approaches as to how they set papers, how they marked exams and so on so there isn't even "fairness" amongst cohort let alone across the country.
Let's face it enough people were not happy that mocks may feed into CAGS because of the variables and because some students don't try as hard or had other commitments that would all be out on hold for real thing etc.
(Fortunately for DS he did well and should be same/similar to cags ).
However the next carnage comes becauee unis have more than likely already entered decisions into UCAS. What are they supposed to do? Are they supposed to unreject those who didn't meet offers to allow mock grades to be submitted? This will have an impact on what is in clearing or not and how early?
It sounds like a knee jerk reaction and not very well thought through.