hmc as I understand it they just check that each answer on a paper has been marked as in the right band. So if it was marked as being eg a Level 3 answer, but the mark awarded had only just crept in to that band, the mark wouldn’t be adjusted even if a second marker would have given it a higher mark within band 3. Obviously if the same thing has happened across a number of questions on a paper, those extra marks could have added up to a higher grade, but the grade wouldn’t change now. Loose please correct me if I’m wrong.
I think it was introduced because it was felt that schools/parents with the money to pay for remarks were gaining an advantage. Which of course wouldn’t be the case if grades weren’t being wrongly awarded in the first place...
When DD sat her Oxford exam (ELAT) each paper was double-marked blind and an average of the two marks was awarded. UNLESS the difference between the two marks was greater than 3, in which case a third marker reviewed it. I know this couldn’t be replicated across the thousands of papers sat at GCSE, but I think the system should be better than it currently is.
It’s even worse at A Level when so much is riding on the results...